SQL Tutorials

SQL CREATE TABLE: How-To Guide

The SQL CREATE TABLE statement adds a table to a database. Using this statement, you can specify the names of the columns in the new table and the types of data each column…
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SQL Subquery: A Complete Guide

An SQL subquery is a query inside another query. It is used in the WHERE or HAVING clause of an SQL statement. Subqueries let you specify the results of one query as an argument…
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SQL Aliases: A Complete Guide

An SQL alias is a reference name for a table or a column. They are used to shorten your queries if you have long table names. Both table and column aliases are defined using…
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SQL Left Join: A Complete Guide

An SQL LEFT JOIN is a type of SQL join. This join returns all the tables from a specified “left” column and the corresponding rows that match a particular condition…
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SQL ORDER BY: A Complete Guide

The SQL ORDER BY statement determines the order in which records are returned by a query. You can return records in ascending or descending order by the value of any column…
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SQL INNER JOIN: A Complete Guide

The SQL INNER JOIN statement returns rows with exact values in two columns across two tables. You can join a table across one or multiple columns. JOIN statements connect…
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SQL Aggregate Functions: A Complete Guide

SQL aggregate functions retrieve information about the data in a database. You can use COUNT to find out how many records are in a database, for instance. Accepted aggregate…
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SQL Group By: A Complete Guide

The SQL GROUP BY statement appears in aggregate functions. It is used to collate the data you select from a query by a particular column. You can specify multiple columns…
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SQL Like: A How-To Guide

The SQL LIKE operator uses wildcards to find data similar to a particular pattern. You can use an underscore to substitute for a single character or a percentage sign to substitute…
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SQL Between: A Complete Guide

The SQL BETWEEN keyword retrieves values that fall within a particular set of values. It is often used to retrieve values between two dates or numbers. This keyword is used…
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SQL ALTER TABLE: A Guide

The SQL ALTER TABLE statement adds, changes, or removes a column in a table. This statement lets you modify a table after it has been created, even if the table stores records….
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SQL WHERE Statement: A How-To Guide

The SQL WHERE clause limits how many records are returned or affected by a command. It is used with the SELECT, UPDATE, and DELETE clauses. You can use the AND keyword to…
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How Is SQL’s Not Equal Operator Used?

The SQL not equal operator is represented by <>. This operator lets you select rows from a database that do not meet a particular condition. The != operator is used…
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SQL Limit: A Beginner’s Guide

The SQL LIMIT statement restricts how many rows a query returns. A LIMIT statement appears at the end of a query, after any ORDER BY statements. You can start a LIMIT statement…
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SQL Delete Row: A Guide

The SQL DELETE statement deletes a row from a database table. You can use the WHERE statement to specify which records should be deleted. If you do not specify a where statement,…
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SQL Add Column: A How-To Guide

There is no SQL ADD COLUMN statement. To add a column to an SQL table, you must use the ALTER TABLE ADD syntax. ALTER TABLE lets you add, delete, or modify columns in a table….
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Learn SQL: A Beginner’s Guide to Data Management

Having knowledge of databases is crucial if you want to explore a career in data. Whether you want to be a data scientist or an engineer, databases will come up at some point….
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SQL EXISTS: How to use this SQL Operator

There are many things you can do to define a query in SQL. One thing you can do to a WHERE clause is check to see if a row exists with the matching parameters in the database….
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SQL Triggers

An SQL Trigger is an event that sets off a number of other events that happens when a user interacts with a particular table. This particular SQL statement helps by validating…
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Using MySQL’s IF(), NULLIF(), and IFNULL() Functions

Just like other programming languages, the structured query language has conditional statements that control the flow of data. The IF function returns a statement if condition…
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