In SQL, we can use a set of nested CASE WHEN statements in SQL to evaluate the multiple conditions and return a different result based on the defined conditions. We can define the syntax of a nested CASE WHEN statement as shown in the following: SELECT CASE WHEN condition1 THEN result1 W...
SQL Server Subquery with nested if else conditionSQL uses "case expressions" instead of if/else s...
Loop Join is usually TRUE in the executions Plan when the inner side of the table is sorted (indexed, except when joining and where condition is in the same column), unless the inner side of the structure contains less than 1.280 +1 per MB data pages available to the SQL Server data...
In this case, the row is complemented by NULL values for the columns of the inner tables. The result row is passed to the final check for the output or into the next nested loop, but only if the row satisfies the join condition of all embedded outer joins. ...
Suppose that our WHERE condition P(T1,T2,T3) can be represented by a conjunctive formula: P(T1,T2,T2) = C1(T1) AND C2(T2) AND C3(T3). In this case, MySQL actually uses the following nested-loop algorithm for the execution of the query with inner joins: ...
IN param3 int, IN param4 int, IN param5 bigint) BEGIN DECLARE EXIT HANDLER FOR SQLEXCEPTION BEGIN GET DIAGNOSTICS CONDITION 1 @sqlstate = RETURNED_SQLSTATE, @errno = MYSQL_ERRNO, @text = MESSAGE_TEXT; SET @full_error = CONCAT("ERROR ", @errno, " (", @sqlstate, "): ", @text)...
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SQL Server Subquery with nested if else conditionSQL uses "case expressions" instead of if/else ...
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3.The OPTIMIZER_FEATURES_ENABLE initialization parameter is set to a release before Oracle Database 11g. In this case, Oracle Database uses the original implementation for nested loop joins. 没有11g的环境,以后可以注意一下。最近看了一些sql调优化的例子,总结出嵌套循环的使用情况: ...