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STRING_SPLIT (Transact-SQL)

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Applies to: SQL Server 2016 (13.x) and later Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics SQL analytics endpoint in Microsoft Fabric Warehouse in Microsoft Fabric

STRING_SPLIT is a table-valued function that splits a string into rows of substrings, based on a specified separator character.

Compatibility level 130

STRING_SPLIT requires the compatibility level to be at least 130. When the level is less than 130, the Database Engine is unable to find the STRING_SPLIT function.

To change the compatibility level of a database, refer to View or change the compatibility level of a database.

Note

Compatibility configuration isn't needed for STRING_SPLIT in Azure Synapse Analytics.

Transact-SQL syntax conventions

Syntax

STRING_SPLIT ( string , separator [ , enable_ordinal ] )

Arguments

string

An expression of any character type (for example, nvarchar, varchar, nchar, or char).

separator

A single character expression of any character type (for example, nvarchar(1), varchar(1), nchar(1), or char(1)) that is used as separator for concatenated substrings.

enable_ordinal

Applies to: Azure SQL Database, Azure SQL Managed Instance, Azure Synapse Analytics (serverless SQL pool only), and SQL Server 2022 (16.x) and later versions

An int or bit expression that serves as a flag to enable or disable the ordinal output column. A value of 1 enables the ordinal column. If enable_ordinal is omitted, NULL, or has a value of 0, the ordinal column is disabled.

Return types

If the ordinal output column isn't enabled, STRING_SPLIT returns a single-column table whose rows are the substrings. The name of the column is value. It returns nvarchar if any of the input arguments are either nvarchar or nchar. Otherwise, it returns varchar. The length of the return type is the same as the length of the string argument.

If the enable_ordinal argument is passed a value of 1, a second column named ordinal is returned that consists of the 1-based index values of each substring's position in the input string. The return type is bigint.

Remarks

STRING_SPLIT inputs a string that has delimited substrings and inputs one character to use as the delimiter or separator. Optionally, the function supports a third argument with a value of 0 or 1 that disables or enables, respectively, the ordinal output column.

STRING_SPLIT outputs a single-column or double-column table, depending on the enable_ordinal argument.

  • If enable_ordinal is NULL, omitted, or has a value of 0, STRING_SPLIT returns a single-column table whose rows contain the substrings. The name of the output column is value.

  • If enable_ordinal has a value of 1, the function returns a two-column table, including the ordinal column that consists of the 1-based index values of the substrings in the original input string.

The enable_ordinal argument must be a constant value, not a column or variable. It must also be either a bit or int data type with a value of 0 or 1. Otherwise, the function raises an error.

The output rows might be in any order. The order isn't guaranteed to match the order of the substrings in the input string. You can override the final sort order by using an ORDER BY clause on the SELECT statement, for example, ORDER BY value or ORDER BY ordinal.

0x0000 (char(0)) is an undefined character in Windows collations and can't be included in STRING_SPLIT.

Empty zero-length substrings are present when the input string contains two or more consecutive occurrences of the delimiter character. Empty substrings are treated the same as are plain substrings. You can filter out any rows that contain the empty substring by using the WHERE clause, for example WHERE value <> ''. If the input string is NULL, the STRING_SPLIT table-valued function returns an empty table.

As an example, the following SELECT statement uses the space character as the separator:

SELECT value FROM STRING_SPLIT('Lorem ipsum dolor sit amet.', ' ');

In a practice run, the preceding SELECT returned following result table:

value
Lorem
ipsum
dolor
sit
amet.

The following example enables the ordinal column by passing 1 for the optional third argument:

SELECT * FROM STRING_SPLIT('Lorem ipsum dolor sit amet.', ' ', 1);

This statement then returns the following result table:

value ordinal
Lorem 1
ipsum 2
dolor 3
sit 4
amet. 5

Examples

A. Split comma-separated value string

Parse a comma-separated list of values and return all non-empty tokens:

DECLARE @tags NVARCHAR(400) = 'clothing,road,,touring,bike'

SELECT value
FROM STRING_SPLIT(@tags, ',')
WHERE RTRIM(value) <> '';

STRING_SPLIT returns an empty string if there's nothing between separator. The condition RTRIM(value) <> '' removes empty tokens.

B. Split comma-separated value string in a column

Product table has a column with comma-separate list of tags shown in the following example:

ProductId Name Tags
1 Full-Finger Gloves clothing,road,touring,bike
2 LL Headset bike
3 HL Mountain Frame bike,mountain

Following query transforms each list of tags and joins them with the original row:

SELECT ProductId, Name, value
FROM Product
    CROSS APPLY STRING_SPLIT(Tags, ',');

Here's the result set.

ProductId Name Value
1 Full-Finger Gloves clothing
1 Full-Finger Gloves road
1 Full-Finger Gloves touring
1 Full-Finger Gloves bike
2 LL Headset bike
3 HL Mountain Frame bike
3 HL Mountain Frame mountain

Note

The order of the output might vary as the order is not guaranteed to match the order of the substrings in the input string.

C. Aggregation by values

Users must create a report that shows the number of products per each tag, ordered by number of products, and to filter only the tags with more than two products.

SELECT value as tag, COUNT(*) AS [number_of_articles]
FROM Product
    CROSS APPLY STRING_SPLIT(Tags, ',')
GROUP BY value
HAVING COUNT(*) > 2
ORDER BY COUNT(*) DESC;

D. Search by tag value

Developers must create queries that find articles by keywords. They can use following queries:

To find products with a single tag (clothing):

SELECT ProductId, Name, Tags
FROM Product
WHERE 'clothing' IN (SELECT value FROM STRING_SPLIT(Tags, ','));

Find products with two specified tags (clothing and road):

SELECT ProductId, Name, Tags
FROM Product
WHERE EXISTS (SELECT *
    FROM STRING_SPLIT(Tags, ',')
    WHERE value IN ('clothing', 'road'));

E. Find rows by list of values

Developers must create a query that finds articles by a list of IDs. They can use following query:

SELECT ProductId, Name, Tags
FROM Product
JOIN STRING_SPLIT('1,2,3',',')
    ON value = ProductId;

The preceding STRING_SPLIT usage is a replacement for a common antipattern. Such an antipattern can involve the creation of a dynamic SQL string in the application layer or in Transact-SQL. Or an antipattern can be achieved by using the LIKE operator. See the following example SELECT statement:

SELECT ProductId, Name, Tags
FROM Product
WHERE ',1,2,3,' LIKE '%,' + CAST(ProductId AS VARCHAR(20)) + ',%';

F. Find rows by ordinal values

The following statement finds all rows with an even index value:

SELECT *
FROM STRING_SPLIT('Austin,Texas,Seattle,Washington,Denver,Colorado', ',', 1)
WHERE ordinal % 2 = 0;

The above statement returns the following table:

value ordinal
Texas 2
Washington 4
Colorado 6

G. Order rows by ordinal values

The following statement returns the split substring values of the input string and their ordinal values, ordered by the ordinal column:

SELECT * FROM STRING_SPLIT('E-D-C-B-A', '-', 1) ORDER BY ordinal DESC;

The above statement returns the following table:

value ordinal
A 5
B 4
C 3
D 2
E 1

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