sql-server-2008 - TSQL は、子の結果セットから変数を割り当てて、クエリの繰り返しを回避します

Question

このようなクエリを繰り返さずに、以下のコードを効率的に改善する方法はありますか?

注:この場合、引数を割り当てるための既知の数の要素があります。

SELECT  @var0 = Field_A FROM Table_0 
JOIN Table_1 ON (Table_0.PK = Table_1.FK) 
WHERE Table_1.PK = 1 AND TABLE_0.Field_B = 1;

SELECT  @var1 = Field_A FROM Table_0 
JOIN Table_1 ON (Table_0.PK = Table_1.FK) 
WHERE Table_1.PK = 1 AND TABLE_0.Field_B = 2;

SELECT  @var2 = Field_A FROM Table_0 
JOIN Table_1 ON (Table_0.PK = Table_1.FK) 
WHERE Table_1.PK = 1 AND TABLE_0.Field_B = 3;

Answer 1

このようなもの：

SELECT
    @var0 = MAX( CASE table_0.field_b WHEN 1 THEN field_a END )
    , @var1 =   MAX( CASE table_0.field_b WHEN 2 THEN field_a END )
    , @var2 =   MAX( CASE table_0.field_b WHEN 3 THEN field_a END )
FROM 
    table_0
JOIN
    table_1 
    ON 
        TABLE_0.PK = TABLE_1.FK