For example, the following query will not work as desired.īecause the IN operator accepts a list of values e.g., (1,2,3) not a string that consists of a list of values (‘1,2,3’). Therefore, the query may not return any result. If you supply this result to the IN operator, the query is not working. It means you cannot use the result of the GROUP_CONCAT() function for IN operator e.g., within a subquery.įor example, the GROUP_CONCAT() function returns the result of values: 1 2, and 3 as the ‘1,2,3’ string. The GROUP_CONCAT() function returns a single string, not a list of values. MySQL GROUP_CONCAT function: common mistakes
Note that GROUP_CONCAT() function concatenates string values in different rows while the CONCAT_WS() or CONCAT()function concatenates two or more string values in different columns.
#MYSQL CONCATENATE STRINGS CODE#
To get all countries where customers locate as a comma-separated string, you use the GROUP_CONCAT() function as follows:ĬONCAT_WS( ', ', contactLastName, contactFirstName)Ĭustomers Code language: SQL (Structured Query Language) ( sql ) Let’s take a look at the customers table in the sample database.
In case you need more than this, you can extend the maximum length by setting the group_concat_max_len system variable at SESSION or GLOBAL level. by default, the maximum length of the return string is 1024. The GROUP_CONCAT function returns a binary or non-binary string, which depends on the arguments. It returns NULL if there was no matching row found or all arguments are NULL values. The GROUP_CONCAT function ignores NULL values. If you do not specify a separator, the GROUP_CONCAT function uses a comma (,) as the default separator. The SEPARATOR specifies a literal value inserted between values in the group. If you want to sort the values in the descending order, you need to specify explicitly the DESC option. By default, it sorts the values in ascending order. The ORDER BY clause allows you to sort the values in ascending or descending order before concatenating. The DISTINCT clause allows you to eliminate duplicate values in the group before concatenating them. T Code language: SQL (Structured Query Language) ( sql ) Now, we will concatenate FirstName and LastName to get FullName and City, State and PinNo to get Address using CONCAT Function.INSERT INTO t(v) VALUES( 'A'),( 'B'),( 'C'),( 'B') So, the Student table is : Select * From Student StudentId Student(FirstName, LastName, Class, City, State, PinNo ) Now inserting some data to the Student table : INSERT INTO To demonstrate create a table named Student. SELECT CONCAT('geeks', 'for', 'geeks', NULL) AS ConcatenatedString Įxample-4 : In this example we are going to concatenate string between column of a table. SELECT CONCAT(19, 10, 5.60) AS ConcatenatedNumber Įxample-3 : Concatenating string which includes a NULL String using CONCAT Function. SELECT CONCAT('geeks', 'for', 'geeks') AS ConcatenatedString Įxample-2 : Concatenating numeric string using CONCAT Function.
Example-1 : Concatenating 3 string using CONCAT Function. If any of the input string is NULL then it returns NULL. Returns : It returns a new string after concatenating all input string.
: The input string which we want to concatenate. Parameter : This method accepts N argument.