fix error: "Cannot resolve collation conflict…"

In MS SQL SERVER, the collation can be set in column level. When compared 2 different collation column in the query, this error comes up.

SELECT ID FROM ItemsTable

INNER JOIN AccountsTable

WHERE ItemsTable.Collation1Col = AccountsTable.Collation2Col

If columns ItemsTable.Collation1Col and AccountsTable.Collation2Col have different collation, it will generate the error “Cannot resolve collation conflict for equal to operation“.

To resolve the collation conflict add following keywords around “=” operator.

SELECT ID FROM ItemsTable

INNER JOIN AccountsTable

WHERE ItemsTable.Collation1Col COLLATE DATABASE_DEFAULT

 = AccountsTable.Collation2Col COLLATE DATABASE_DEFAULT

Collation can affect following areas:

1) Where clauses

2) Join predicates

3) Functions

4) Databases (e.g. TempDB may be in a different collation database_default than the other databases some times)