SQL Server replace, remove all after certain character

Use LEFT combined with CHARINDEX:

UPDATE MyTableSET MyText = LEFT(MyText, CHARINDEX(';', MyText) - 1)WHERE CHARINDEX(';', MyText) > 0

Note that the WHERE clause skips updating rows in which there is no semicolon.

Here is some code to verify the SQL above works:

declare @MyTable table ([id] int primary key clustered, MyText varchar(100))insert into @MyTable ([id], MyText)select 1, 'some text; some more text'union all select 2, 'text again; even more text'union all select 3, 'text without a semicolon'union all select 4, null -- test NULLsunion all select 5, '' -- test empty stringunion all select 6, 'test 3 semicolons; second part; third part;'union all select 7, ';' -- test semicolon by itself    UPDATE @MyTableSET MyText = LEFT(MyText, CHARINDEX(';', MyText) - 1)WHERE CHARINDEX(';', MyText) > 0select * from @MyTable

I get the following results:

id MyText-- -------------------------1  some text2  text again3  text without a semicolon4  NULL5        (empty string)6  test 3 semicolons7        (empty string)

For the times when some fields have a ";" and some do not you can also add a semi-colon to the field and use the same method described.

SET MyText = LEFT(MyText+';', CHARINDEX(';',MyText+';')-1)

Could use CASE WHEN to leave those with no ';' alone.

    SELECT    CASE WHEN CHARINDEX(';', MyText) > 0 THEN    LEFT(MyText, CHARINDEX(';', MyText)-1) ELSE    MyText END    FROM MyTable