In C#, the switch statement serves as a control structure that enables the execution of distinct code blocks based on the value of a variable. It is frequently utilized when there is a need to compare a variable with multiple constant values and to carry out various actions according to the...
PRIMARY Outermost SELECT UNION Second or later SELECT statement in a UNION DEPENDENT UNION Second or later SELECT statement in a UNION, dependent on outer query UNION RESULT Result of a UNION. SUBQUERY First SELECT in subquery DEPENDENT SUBQUERY First SELECT in subquery, dependent on outer query D...
AI代码解释 {EXPLAIN|DESCRIBE|DESC}tbl_name[col_name|wild]{EXPLAIN|DESCRIBE|DESC}[explain_type]{explainable_stmt|FORCONNECTIONconnection_id}{EXPLAIN|DESCRIBE|DESC}ANALYZEselect_statementexplain_type:{FORMAT=format_name}format_name:{TRADITIONAL|JSON|TREE}explainable_stmt:{SELECTstatement|TABLEstatement|DELET...
{explainable_stmt|FORCONNECTION connection_id} {EXPLAIN|DESCRIBE|DESC} ANALYZE select_statement explain_type: { FORMAT=format_name } format_name: { TRADITIONAL|JSON|TREE } explainable_stmt: {SELECTstatement|TABLEstatement|DELETEstatement|INSERTstatement|REPLACE statement|UPDATEstatement } 示例: EXPLAIN fo...
Optimizer. You can switch to the Version 2 format by setting the value of the explain_json_format_version server system variable to 2, as shown herefor the same EXPLAIN statement used in the previous example: mysql> SELECT @@explain_json_format_version; +---+ | @@explain_json_format...
控制,详见 Section 5.1.1, “Configuring the Server 参考文档 EXPLAIN Output Format EXPLAIN Statement Extended EXPLAIN Output Format Estimating QueryPerformance MySQL中explain执行计划额外信息字段(Extra详解 explain参数详解 最官方 mysql explain type 字段解读 What does eq_ref and ref types mean ...
4. The index has 4 columns Non clustered index scan will be used Page range scan will not be used _ Table SYSIBM SYSPACKAGE _ Index SYSIBM DSNKKX01 _ PLAN_TABLE details for step FPEM762 This statement was explained at bind time Command ===> ___ F1=Help F2=Split F3=Exit F7=Up F8...
子查询的可缓存性不同于查询结果在查询缓存中的缓存(8.10.3.1 How the Query Cache Operates)。 子查询缓存在查询执行期间发生,而查询缓存仅在查询执行完成后才用于存储结果。 2.3 非查询语句(non-SELECT statements) 非查询语句(non-SELECT statements)的 select_type 值的显示受影响表的语句类型(statement type)。
| REPLACE statement | UPDATE statement } 示例: EXPLAIN format = TRADITIONAL json SELECT tt.TicketNumber, tt.TimeIn, tt.ProjectReference, tt.EstimatedShipDate, tt.ActualShipDate, tt.ClientID, tt.ServiceCodes, tt.RepetitiveID, tt.CurrentProcess, tt.CurrentDPPerson, ...
explainable_stmt: {SELECT statement | TABLE statement | DELETE statement | INSERT statement | REPLACE statement | UPDATE statement } 常用的是方式二,示例: explainselect*fromsalarieswherefrom_date='1996-12-02';-- 以json 形式展示结果:explain format=jsonselect*fromsalarieswherefrom_date='1996-12-02...