Concat in SQL

The SQL CONCAT function is used to concatenate or combine two or more strings into a single string. It takes two or more arguments, which can be either text values or columns, and returns a combined string.

This function is particularly useful when working with databases that store data in separate columns, but you need to combine that data for reporting or display purposes. The Concat function is available in most SQL databases and can be used with a variety of data types. In this blog post, we will explore the Concat function in more detail, including its syntax, examples of how to use it, and tips for getting the most out of this powerful SQL function.

String Functions in SQL

In programming languages, a string is a set of characters that is used to declare texts. In terms of SQL Server, SQL string data types can be divided into two classes – Character strings and Unicode character strings.

A string function accepts a string value as input and returns a string value regardless of the data type. Developers can use many of SQL Server’s built-in string functions.

Some of the popular string functions are listed below:

• Upper
• Lower
• Concat
• Stuff
• Substring
• Replace
• Reverse
• Left
• Right

The syntax is as follows:

CONCAT(string1, string2, ...)

Example:

SELECT CONCAT('Hello', ' ', 'World') as greetings;

Result :

Concatenating the Numerical Data Using the Concat Function

In SQL, numerical values must be converted to text before they can be concatenated using the CONCAT function. This can be done using type casting or string functions like TO_CHAR or CAST.

Example:

SELECT CONCAT('The number is: ', CAST(100 AS VARCHAR(10))) AS result;

Result:

CONCAT Function With Null Value

In SQL, if any of the arguments passed to the CONCAT function is NULL, the result of the concatenation will also be NULL.

Example:

SELECT CONCAT('Hello', NULL, 'World') as greetings;

Result:

Line Feed(n) in CONCAT Function

In SQL, the line feed character n can be included in a concatenated string using the CONCAT function by including it as a literal string in the arguments.

Example:

SELECT CONCAT('Line 1n', 'Line 2n', 'Line 3') as result;

Result:

Carriage Return(r) in Concat Function in SQL:

In SQL, the carriage return character r can be included in a concatenated string using the CONCAT function by including it as a literal string in the arguments.

Example:

SELECT CONCAT('Line 1r', 'Line 2r', 'Line 3') as result;

Result:

Conclusion:

The SQL CONCAT function is a useful tool for combining strings or text values into a single string. It can be used with text values, columns, and numerical values that have been converted to text. The function can also include line feed and carriage return characters as needed. However, it’s important to remember that if any of the arguments passed to the CONCAT function is NULL, the result of the concatenation will also be NULL.

FAQ’s

Q1 What is concatenation in SQL?

Concatenation is the process of combining two or more strings into a single string. In SQL, this can be achieved using the CONCAT() function or the “||” operator.

Q2 How do I use the CONCAT() function in SQL?

The syntax for using the CONCAT() function is as follows:

SELECT CONCAT(string1, string2, …, string_n)
FROM table_name;

Q3 How do I concatenate NULL values in SQL?

The behaviour of concatenating NULL values in SQL depends on the specific RDBMS being used. In some databases, concatenating a NULL value with a string returns NULL, while in others it returns the string. It is best to check the documentation of your specific RDBMS to determine how it handles the concatenation of NULL values.