SQL Practice Test

Structured Query Language
SQL Practice Test

SQL (Structured Query Language) is a standardized programming language for managing relational databases and performing operations on the data contained within them. SQL, which was first developed in the 1970s, is now widely used by database administrators, developers writing data integration scripts, and data analysts setting up and running analytical queries.

Modifying database table and index structures, as well as adding, updating, and removing rows of data, and obtaining subsets of information from within a database for transaction processing and analytics applications, are all possible with SQL. 

Queries and other SQL actions are expressed as statements, which are commonly utilized. Select, add, insert, update, delete, create, change, and truncate are all SQL statements.

In 1986, the American National Standards Institute (ANSI) approved SQL as a standard, and in 1987, the International Organization for Standardization (ISO) approved it. The standard has since been updated to incorporate a broader range of functions. Despite the availability of standards, most SQL code must be modified in some way before it can be ported to multiple database systems.

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SQL Certification

SQL Certification Importance

SQL certification will provide you an advantage over competitors with similar abilities and experience. Of course, experience and technical knowledge are crucial, but when candidates with identical profiles must be screened, credentials become the determining factor. There are many certificates, and you should pursue them one by one depending on the position you are going for and your prior experience. Certifications can also assist you in obtaining better projects and jobs within your organization. Certifications help your new team understand your specialty and essential talents if you’ve changed teams within the same organization.

Certifications will help you advance up the corporate ladder and into higher-paying jobs more quickly than your peers. Take a look at the following average salaries in the United States:

  • SQL developer: $85,000
  • SQL database administrator: $95,000
  • Senior SQL database administrator: $108,000

SQL Certification Cost

Microsoft certification exams are known for being difficult, with questions that would stump even the most experienced SQL developers and database professionals. You must complete a prerequisite course and pass the certification exam to receive a SQL Server certification. The cost of SQL certification training ranges from $1,785 to $2,975, with the exam costing roughly $165.

Most Valuable SQL Certifications (SQL Classes) :

  1. Microsoft Certified: Azure Data Fundamentals
  2. Oracle Database SQL Certified Associate Certification
  3. IBM Certified Database Associate
  4. Oracle Certified Professional, MySQL 5.7 Database Administrator Certification
  5. EDB PostgreSQL 12 Associate Certification

SQL Career

SQL has a variety of functions to play in a data-centric organization, thus SQL specialists who can think analytically and apply it to SQL are in high demand in today’s software industry. SQL is an excellent career choice for people who enjoy working with data and solving problems.

Job positions:

  • Database Administrator (DBA)
  • Database Developer
  • Data base testers
  • Data Scientist
  • ETL Developer
  • Data Application Interface Developer
  • BI Application Developer
  • BI Administration
  • Big Data Expert
  • Cloud Database Expert
  • Database Migration Engineer
  • Data Analyst
  • BI Reporting Engineer
  • BI Solution Architect (SME)
  • NoSQL DBA
  • Big Data Architect

A Guide to SQL PDF

Learning SQL the “proper way” can be tough with all of the materials accessible. It isn’t easy to figure out the ideal technique to learn SQL because everyone learns things differently. SQL cheat sheet PDF, pl/SQL programs for practice PDF, SQL query questions and answers for practice PDF, and SQL certification questions and answers PDF are some of the study tools for learning SQL. We recommend taking a free SQL test to learn more about SQL.

SQL Questions and Answers

The main and most extensively used programming language for relational databases is Structured Query Language (SQL). It’s used to manage and organize data in a variety of systems with a variety of data linkages.

The best programming language used in relational database management systems is SQL, which stands for Structured Query Language.

Because SQL is the most widely used database language, it may be utilized by practically any enterprise that requires relational data storage. SQL queries are used to obtain data from the database, although their performance varies.

SQL Server is a relational database management system (RDBMS) developed by Microsoft. T-SQL stands for Transact-SQL, a proprietary language developed by Microsoft and Sybase. Version 1.0 of SQL Server was launched in 1989.

SQL injection is a type of attack in which malicious code is embedded in strings and then supplied to a SQL Server instance for parsing and execution.

T-SQL is a procedural language used by Microsoft’s SQL Server. This version of SQL has declared variables, transaction control, error and exception management, and row processing. The syntax of T-SQL differs from that of PL-SQL.

Mastering the fundamental ideas of SQL and working with SQL databases should take an average learner roughly two to three weeks.

The official pronunciation of “MySQL” is “My Ess Que Ell” (not “my sequel”), but some people don’t mind if you say it like “my sequel” or something else. Microsoft SQL Server is frequently misheard as “sequel server”:

You can use the ALTER TABLE command to add columns to an existing table in SQL by inserting the column name and description.

Choose the SQL code you want to uncomment or comment out. Click anywhere in the line of code for a single line. Drag the pointer through the lines of code for several lines. Toggle Comment by right-clicking on the selected SQL code. If the line was formerly active, it is now a comment.

Users build their own databases (administrators, developers, and testers who have access to create databases). Right-click on the databases folder and connect to SQL Server instance. The following screen will appear when you select a new database. Click OK once you’ve entered your database name in the database name area. A database called testdb will be built.

In the database, the CREATE VIEW statement generates a new view. After the construct VIEW keywords, specify the name of the view you want to create. Second, if you wish to replace an existing view that already exists, use the OR REPLACE option. OR REPLACE has no effect if the view does not exist. Third, create a column list for the view. The view’s columns are derived by default from the Choose statement’s select list. Finally, define the view by using a SELECT statement. Data from tables or views can be queried using the SELECT statement.

The SQL DROP TABLE statement deletes a table’s definition as well as all of its data, indexes, triggers, constraints, and permissions.

SQL protection parameters are the only proven approach to defend a website from SQL injection attacks. These are custom values that were added to the SQL query during execution. The SQL protection parameters are defined using a @ marker in a SQL statement:

The begin and finish values are both included in the Between statement. The SQL Between operator is similar to SQL IN operators when used sequentially. The values defined as part of the Between range are inclusive; that is, the range’s values are included at both the start and finish values.

When you have a decent plan in place, SQL is not difficult to learn. You’ll also require the appropriate resources to back up your efforts. In reality, SQL is one of the most beginner-friendly languages.

“Procedural Language Extensions to the Structured Query Language” is what PL/SQL stands for. SQL is a widely used language in relational database management systems for querying and updating data (RDBMS).

DELETE FROM should be used with the name of the table from which you want to remove a row. Write the condition that specifies the row in WHERE. If you’re looking for a certain row, it’s advisable to write the condition in the column with unique values. If there are many rows with the name ‘Ellen Thornton,’ they will all be eliminated. If no such name exists, no rows are eliminated.

NoSQL databases can contain a variety of data types and are not as structured as SQL databases. As a result, non-relational databases offer greater adaptability and flexibility, making them a better alternative for dealing with vast amounts of unstructured, unconnected data.

In general, the larger the dataset, the more likely a NoSQL database is the preferable choice. Non-relational databases excel in scalability and availability, making them excellent for social networks and real-time applications (for example, online gaming and instant messaging).

  • SELECT @@version is a straightforward approach to accomplish this.
  • Another approach is to pick Properties from the right-click menu on the SQL Server instance name in SSMS.
  • You can also use the SERVERPROPERTY function to acquire information about SQL Server’s version.

To build a stored procedure in SQL Server, follow these steps: 

  • On the SSMS toolbar, select New Query.
  • Create a procedure by typing (or pasting) a CREATE PROCEDURE statement
  • On the toolbar, click the Execute button.
  • The stored procedure will now be added to the database. In the Object Explorer, it’s under the Stored Procedures node.

There are two ways to make a temporary table. Using an INTO statement within a select query is the simplest way to create a temporary table. Let’s make a temporary table with all of the male student records from the student table’s names, age, and gender.

Microsoft SQL Server is a database management solution for relational databases. It’s a database server, which is a software product whose primary function is to store and retrieve data as needed by other software applications, which can run on the same machine or across a network (including the Internet).

Make a contingency plan.. 

  • Connect to your SQL Server instance with SQL Server Management Studio (SSMS).
  • In Object Explorer, expand the Databases node.
  • Right-click the database, then select “Back up” from the Tasks menu. 
  • Confirm that the path for your backup is accurate under Destination.
  • To create a database backup, select OK.

We can modify the column in SQL Server whenever we want. When the column name is meaningless or does not serve the purpose for which it was created, we shall rename it. Before updating the column’s name, it must be confirmed that we have altered permission on the object. Because when we rename a column, it does not mean that all references to that column will be altered as well, SQL Server has some limitations when altering the column name. All objects in the renamed column must be manually modified.

You must connect to the target instance of SQL Server to migrate Access databases to SQL Server. When you connect, SSMA retrieves database metadata from the SQL Server instance and displays it in the SQL Server Metadata Explorer. SSMA keeps track of the SQL Server instance you’re connecting to, but it doesn’t keep track of passwords.

The SQL script is a collection of commands saved as a file in SQL Scripts that includes one or more SQL statements. SQL Scripts are used to create, run, edit, view, and delete script files.

  • When utilizing SQL Scripts, keep the following points in mind:
  • SQL * Plus instructions are ignored at run time in SQL scripts.
  • In SQL scripts, there is no interaction between SQL scripts and SQL commands. 
  • SQL commands are copied and pasted from the SQL script editor.
  • The bound variables are not supported by SQL script.

The SELECT statement’s DISTINCT clause is used to filter duplicate rows from the result set. When you choose a single column or a group of columns, you can utilize DISTINCT.

SQL GROUP BY is most commonly used in conjunction with aggregate procedures such as COUNT(), MAX(), MIN(), SUM(), and AVG(). It divides the result set into groups based on one or more columns, basically constructing summary rows for each group. Rather than continuous values, these groups are frequently based on categorical values.

You can use a LIKE clause as the condition in a WHERE clause to select records where a string fits a specified pattern. List the name of the column (e.g., city) after WHERE, then a LIKE clause describing the text pattern to search for (e.g., ‘S % o__’).

Because the current SQL standard incorporates “Persistent Stored Modules,” SQL is now a turing complete language (PSMs). In a nutshell, a PSM is Oracle’s standard version of the PL/SQL language (and other similar procedural extensions of current DBMS). SQL became turing complete with the addition of these PSMs.

To handle NULL values, the SQL Coalesce and IsNull methods are utilized. The NULL values are substituted with the user-defined value throughout the expression evaluation process. The SQL Coalesce function evaluates the arguments in the specified order and always returns the first non-null value from the parameter list.

SQL Slammer takes advantage of the way MS SQL servers handle input on port 1434 of the SQL Server Resolution Service. Only 376 bytes in a specially designed packet delivered over the Internet can remotely compromise a susceptible server. The SQL worm, like Code Red, has no files and simply exists in memory.

The SQL COUNT () method returns the number of rows in a table that satisfy the WHERE clause’s requirements. It determines the number of rows or column values that are not NULL. If there were no matching rows, COUNT () yields 0. The syntax shown above is the SQL 2003 ANSI standard syntax. This clarifies how the COUNT () function in SQL is utilized.

The following is a step-by-step guide to downloading SQL on Windows 10:

  • Step 1: For Microsoft SQL Server downloads, go to the official page and download the SQL Server installer. Microsoft offers two free SQL Download editions for use with MS SQL Server:
  • Step 2: Select “Download Now” from the drop-down menu. SQL Server 2017-SSEI-Dev.exe’ will be used to install SQL Server.

To link three tables, first join two tables with a join statement to create a temporary joined table. Then, to join the third table, use a second join statement. Type SELECT, then the names of the columns you want to query. For each of the three columns you want to query, type the name of the column.

The greatest method to practice SQL is to acquire hands-on experience solving real-world challenges, which allows you to receive immediate feedback on your work.

By default, the ORDER BY command organizes the result set in ascending order. Use the DESC keyword to sort the results in ascending order. Use the ASC command to sort the data returned in ascending order.

The UPDATE statement is used to make changes to data in a table. You can alter the values in one or more columns of a single row or several rows.

  • After the UPDATE keyword, enter the name of the table for which you want to update data.
  • Second, in the SET clause, define which column you wish to update and the new value. You utilize a list of comma-separated assignments to update values in several columns by providing a value in each column’s assignment in the form of a literal value, an expression, or a subquery.
  • Third, use a condition in the WHERE clause to determine which rows should be updated. The “where” clause is not required. If you leave it out, the UPDATE statement will change all of the rows in the table. 

You should keep in mind that the WHERE clause is quite critical. You may want to update only one row at a time; however, you may forget to utilize the WHERE clause and update all rows of the table.

To acquire the number of employees, the number of employees in each department, the number of employees who hold a given position, and so on, utilize the COUNT function in the SELECT query.

Using a SELECT command in SQL Server, we may quickly see a table. The SELECT statement is mostly used to retrieve data from database objects. A table, on the other hand, is a database object whose data can be retrieved using the SELECT query.

In SQL Server, a database is made up of a series of tables that hold a certain set of structured data. A table is made up of rows, which are also called records or tuples, and columns, which are called attributes.

Nonrelational databases are referred to as ‘NoSQL,’ and these databases store data in a way that differs from relational tables. NoSQL databases, on the other hand, may be queried via idiomatic language APIs, declarative structured query languages, and query-by-example languages, earning them the moniker “not only SQL” databases.

The SQL Developer, often known as an Integrated Development Environment or IDE, provides a workspace for developing databases using SQL programming. It is an Oracle open-source utility with a user-friendly graphical user interface (GUI) that supports all of Oracle’s other tools.

The Construct INDEX statement is used to create a non-clustered index: CREATE [NONCLUSTERED] INDEX index name ON table name (column list); Code language: SQL (Structured Query Language) (sql) In this syntax: After the CREATE NONCLUSTERED INDEX clause, specify the index’s name.

Duplicates can be found by grouping rows, using the COUNT aggregate function, and filtering rows with a HAVING clause. Only duplicate records—those with the same product name and category—are returned by this query:

You must supply the old and new table names when using the SQL RENAME TABLE command to change the name of a single or many tables.

You’ll need to use the ALTER table statement first, then the RENAME TABLE statement. When you alter the table name, the table’s columns stay the same and will not change unless you modify them.

To uninstall a SQL Server failover cluster, utilize SQL Server Setup’s Remove Node capability to remove each node individually.

To define a range to test, use the SQL BETWEEN operator. For retrieving data for a particular range, use the BETWEEN operator with the SELECT query. The BETWEEN operator can also be used to indicate a range in DELETE, UPDATE, and INSERT statements. You can use the BETWEEN SQL function to specify a number range, two dates, and text.

The SQL CASE statement is useful if you need to examine numerous conditional statements. The CASE statement in SQL gives results based on a set of conditions being met. It’s quite adaptable and may be used in a variety of ways. You can use it to display values, order sort results, and filter records, for example. It checks for stated conditions and returns the result for the first one that is true.

In SQL Server, a function is a database object. It’s essentially a sequence of SQL statements that simply accept input arguments, conduct operations, and return the outcome.

The SQL code -904 indicates that a DB2 query was not successfully executed owing to an unavailable resource. DB2 also provides the name, kind of resource unavailable, and reason.

SQL statements are classified as either Data Manipulation Language (DML) or Data Definition Language (DDL) statements in most cases. DML statements change the status of database objects.

SQL Server Integration Services, or Microsoft SSIS, is a data migration and integration tool that comes with the Microsoft SQL Server database and may be used to extract, integrate, and modify data. SSIS is an ETL (Extract, Transform, and Load) tool.

MySQL is a piece of software, so it has to be treated as such. As a result, it’s regularly updated. SQL is a database language for managing data in relational databases, whereas MySQL is an Open Source Relational Database Management System for managing relational databases.

Practice is the most effective approach to learning SQL. Now, how you begin learning is a different story, and it will be determined by your learning style, the amount of time and money you have to devote to studying, and your ultimate objectives. The most common way for most people to begin learning SQL is to enroll in an online course.

To format the date and/or time in SQL Server, use the T-SQL FORMAT () function. Simply specify the date and time, as well as the format to be used. The format is provided in the form of a format string. The output should be structured according to the format string.

The GETDATE() function is typically used to determine the current date. The DATETIME data type will be returned. This indicates that it will return the current date and time.

You must complete a prerequisite course and pass the certification exam to receive a SQL Server certification. SQL certification course requirements, fees, and duration vary based on the company and level of certification.

You can use a variety of approaches to increase query performance, and the best way to master them is to practice.

To multiply two numbers, use the SQL * (multiply) operator. It works with numerical values.

Exit Acctivate Mobile, close all SQL Server connections, halt processing shipments on shipping workstations, go to SQL Server Configuration Manager, click SQL Server (ACCTIVATE) and Restart service, validate State is “Running”

You can use the following commands to restore the SQL Server database from a backup file:

  • SQL Server Management Studio is a tool for managing SQL Server databases (SSMS)
  • Queries in T-SQL 
  • SqlBackupAndFtp is a SQL backup and FTP application.

Depending on whether you’re using SQL Server, Oracle, MySQL, or PostgreSQL, you use the CEIL or CEILING function to round up to the nearest integer. The CEILING() function in SQL Server is used to round up.

Using the SQL SELECT DISTINCT statement, you can get unique data from a table’s columns. You only need to specify the column name that has a lot of duplicate data and you only want to get the unique data.

The SUM function in SQL can be used to add a bunch of integers to your table. SELECT SUM (column name) FROM table name; In SQL, the SELECT command instructs the computer to retrieve data from the table. In SQL, we specify the table we want to list using the FROM clause.

The SUM function in SQL can be used to add a bunch of integers to your table. SELECT SUM (column name) FROM table name; In SQL, the SELECT command instructs the computer to retrieve data from the table. In SQL, we specify the table we want to list using the FROM clause.

Azure SQL is a set of managed, secure, and intelligent SQL Server database products that run in the Azure cloud. Support modern cloud applications with an intelligent, managed database solution that incorporates serverless computing in Azure SQL Database.

In SQL, the Data Manipulation Language (DML) commands are used to manipulate data records contained in database tables. It is unaffected by changes to the database’s objects and structure. INSERT, UPDATE, and DELETE are the most frequently used DML commands.

Spark SQL is also well-known for its ability to work with both organized and unstructured data. Structured data is data that has a defined schema and a set of fields. Semi-structured data is defined as data that has no separation between the schema and the data.

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