PATINDEX (Transact-SQL)

Artykuł
12/08/2014

Returns the starting position of the first occurrence of a pattern in a specified expression, or zeros if the pattern is not found, on all valid text and character data types.

Ikona łącza do tematu Transact-SQL Syntax Conventions

Składnia

PATINDEX ( '%pattern%' , expression )

Arguments

pattern
Is a character expression that contains the sequence to be found. Wildcard characters can be used; however, the % character must come before and follow pattern (except when you search for first or last characters). pattern is an expression of the character string data type category. pattern is limited to 8000 characters.
expression
Is an expression, typically a column that is searched for the specified pattern. expression is of the character string data type category.

Return Types

bigint if expression is of the varchar(max) or nvarchar(max) data types; otherwise int.

Uwagi

If either pattern or expression is NULL, PATINDEX returns NULL.

PATINDEX performs comparisons based on the collation of the input. To perform a comparison in a specified collation, you can use COLLATE to apply an explicit collation to the input.

Supplementary Characters (Surrogate Pairs)

When using SC collations, the return value will count any UTF-16 surrogate pairs in the expression parameter as a single character. For more information, see Collation and Unicode Support.

0x0000 (char(0)) is an undefined character in Windows collations and cannot be included in PATINDEX.

Examples

A. Using a pattern with PATINDEX

The following example finds the position at which the pattern ensure starts in a specific row of the DocumentSummary column in the Document table.

USE AdventureWorks2012;
GO
SELECT PATINDEX('%ensure%',DocumentSummary)
FROM Production.Document
WHERE DocumentNode = 0x7B40;
GO

Here is the result set.

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(1 row(s) affected)

If you do not restrict the rows to be searched by using a WHERE clause, the query returns all rows in the table and reports nonzero values for those rows in which the pattern was found, and zero for all rows in which the pattern was not found.

B. Using wildcard characters with PATINDEX

The following example uses % and _ wildcards to find the position at which the pattern 'en', followed by any one character and 'ure' starts in the specified string (index starts at 1):

  SELECT PATINDEX('%en_ure%', 'please ensure the door is locked');

Here is the result set.

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PATINDEX works just like LIKE, so you can use any of the wildcards. You do not have to enclose the pattern between percents. PATINDEX('a%', 'abc') returns 1 and PATINDEX('%a', 'cba') returns 3.

Unlike LIKE, PATINDEX returns a position, similar to what CHARINDEX does.

C. Using COLLATE with PATINDEX

The following example uses the COLLATE function to explicitly specify the collation of the expression that is searched.

USE tempdb;
GO
SELECT PATINDEX ( '%ein%', 'Das ist ein Test'  COLLATE Latin1_General_BIN) ;
GO

D. Using a variable to specify the pattern

The following example uses a variable to pass a value to the pattern parameter.

USE AdventureWorks2012; 
GO
DECLARE @MyValue varchar(10) = 'safety'; 

SELECT PATINDEX('%' + @MyValue + '%', DocumentSummary) 
FROM Production.Document
WHERE DocumentNode = 0x7B40;

Here is the result set.

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