string_expression

Is the string expression to be searched. string_expression can be of a character or binary data type.

string_pattern

Is the substring to be found. string_pattern can be of a character or binary data type. string_pattern cannot be an empty string ('').

string_replacement

Is the replacement string. string_replacement can be of a character or binary data type.

Returns nvarchar if one of the input arguments is of the nvarchar data type; otherwise, REPLACE returns varchar.

Returns NULL if any one of the arguments is NULL.

REPLACE 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.

The following example replaces the string cde in abcdefghi with xxx.

SELECT REPLACE('abcdefghicde','cde','xxx');
GO

Here is the result set.

------------
abxxxfghixxx
(1 row(s) affected)

The following example uses the COLLATE function.

SELECT    REPLACE('Das ist ein Test'  COLLATE Latin1_General_BIN,
'Test', 'desk' );
GO

Here is the result set.

------------
Das ist ein desk
(1 row(s) affected)

Reference

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