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Fenton
Fenton

Reputation: 251062

MySql SQL_NO_CACHE Issue Between 5.0 And 5.5

The following query works in MySql 5.0

SELECT SQL_NO_CACHE
    ItemId,
    AnotherColumn
FROM
    TableOne
UNION
SELECT SQL_NO_CACHE
    ItemId,
    AnotherColumn
FROM
    TableTwo

But in MySql 5.5 I get the following error:

MySql.Data.MySqlClient.MySqlException: Incorrect usage/placement of 'SQL_NO_CACHE'

What is the correct placement of SQL_NO_CACHE for UNION queries?

If I put SQL_NO_CACHE on one side of the UNION, will it affect both sides?

Upvotes: 4

Views: 3630

Answers (1)

Fenton
Fenton

Reputation: 251062

As of MySql 5.5.3, you just need to specify SQL_NO_CACHE in the first SELECT of a UNION query:

SELECT SQL_NO_CACHE
    ItemId,
    AnotherColumn
FROM
    TableOne
UNION
SELECT
    ItemId,
    AnotherColumn
FROM
    TableTwo

It applies to the whole query. If you try and specify it in the subsequent SELECT statements it will error (and it is also now allowed in sub-queries).

Upvotes: 6

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