What are SQL string functions?

SQL string functions are built-in functions used to manipulate text (string) data in queries. Common examples include SUBSTRING, TRIM, LENGTH, REPLACE, CONCATENATE, CAST, CONVERT, INSTR, and TO_DATE.

Are SQL string functions the same in all databases?

No. While the core functionality is similar, different RDBMS systems (MySQL, Oracle, SQL Server, PostgreSQL) may use different function names or slightly different syntax for the same operations.

Which SQL function extracts a portion of a string?

The SUBSTRING function extracts a portion of a string. It accepts the source string, the starting position, and optionally the length of the substring to extract.

How do you combine strings in SQL?

Use the CONCATENATE function (or the || operator in standard SQL / Oracle, or the + operator in SQL Server) to combine multiple string values into one.

SQL String Functions | Manipulate Text Data in SQL Queries

SQL > SQL String Functions

In this section, we cover common string functions seen in SQL. Different RDBMS may employ different string functions, and there may also be differences in the syntax for each RDBMS even when the function call is the same. All such differences are explained in each section. Please note that we do not list all possible SQL string functions in this tutorial. Rather, the most commonly used ones are covered.

Key Takeaway: SQL string functions let you transform, search, and extract data from text columns. While the most important ones — like SUBSTRING, TRIM, and LENGTH — are widely available, exact syntax may differ between MySQL, Oracle, SQL Server, and PostgreSQL.

SQL String Function	Description
CAST	Converts data from one data type to another.
CONVERT	Converts data from one data type to another.
CONCATENATE	Combines the results of several columns together.
SUBSTRING	Returns a portion of a string.
INSTR	Finds the starting location of a pattern in a string.
TRIM	Removes specified prefix or suffix from a string. The most common pattern being removed is white space.
LENGTH	Returns the length of a string.
REPLACE	Updates the content of a string.
TO_DATE	Converts a string to a date.

Frequently Asked Questions

What are SQL string functions?: SQL string functions are built-in functions used to manipulate and transform text (string) values in queries. Common examples include SUBSTRING, TRIM, LENGTH, REPLACE, CAST, CONVERT, INSTR, CONCATENATE, and TO_DATE.
Are SQL string functions the same in all databases?: The core functionality is similar, but function names and syntax can vary across RDBMS platforms. For example, string concatenation uses CONCAT() in MySQL, || in Oracle/PostgreSQL, and + in SQL Server.
Which SQL function extracts part of a string?: The SUBSTRING function (also called SUBSTR in Oracle) extracts a portion of a string, given a starting position and optional length.
How do you convert a string to a date in SQL?: In Oracle, use TO_DATE(string, format). In SQL Server use CONVERT or CAST. In MySQL use STR_TO_DATE(string, format). Each database has slightly different syntax for date conversion.

This page was last updated on March 19, 2026.

SQL String Functions

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