The SELECT identifier. This is the sequential number of the SELECT within the query. The value can be NULL if the row refers to the union result of other rows. In this case, the table column shows a value like <unionM,N> to indicate that the row refers to the union of the rows wi...
MySQL explains how it would process the statement, including information about how tables are joined and in which order. For information about using EXPLAIN to obtain execution plan information, see Section 8.8.2, “EXPLAIN Output Format”. 当...
The SELECT identifier. This is the sequential number of the SELECT within the query.The value can be NULL if the row refers to the union result of other rows. In this case, the table column shows a value like <unionM,N> to indicate that the row refers to the union of the rows with...
{explainable_stmt | FOR CONNECTION connection_id}方式三: {EXPLAIN | DESCRIBE | DESC} ANALYZE select_statement 参数说明: explain_type: {FORMAT = format_name }format_name: { TRADITIONAL | JSON | TREE } explainable_stmt: {SELECT statement | TABLE statement | DELETE statement | INSERT statement ...
I am learning fuzzy logic, and I want to implement a simple if statement. I dont want to use the toolbox because later i want to add the fuzzy logic to my matlab code in working on. I checked the matlab help, but it explains how to use ...
I can't explain such a statement by him on the basis of logic. He must have blown his top. 我从逻辑推理方面解释不了他讲的这番话,他想必是神经错乱了. 《现代汉英综合大词典》 He will explain it fully once and for all. 他将把它充分地解释一次就此了结. 《简明英汉词典》 Many theories pur...
as if the statement to be analyzed had been executed in the named database; FOR DATABASE is supported as a synonym. A simple example of use is shown here: mysql> USE b; Database changedmysql> CREATE SCHEMA s1; Query OK, row affected (0.01 sec) mysql> CREATE SCHEMA s2; Query ...
1 row in set (0.00 sec) 1. 2. 3. 4. 5. 6. 7. 若查询服务器工作时间,则可以执行如下语句: mysql> SHOW STATUS LIKE 'Uptime'; +---+---+ | Variable_name | Value | +---+---+ | Uptime | 332933 | +---+---+ 1 row in set...
*** EXPLAIN: -> Count rows in sbtest1 1 rowin set ( sec) If there isn’t a where condition, or groupby, or anything else and just asimple count query, it does not us the time for that step or howmany rows were read orwhich index was used. I think here its a bit too...
EXPLAIN Statement Extended EXPLAIN Output Format Estimating Query Performance MySQL中explain执行计划中额外信息字段(Extra)详解 explain参数详解 最官方的 mysql explain type 字段解读 What does eq_ref and ref types mean in MySQL explain 面试官:不会看 Explain执行计划,简历敢写 SQL 优化?