assign value to variable in sql select statement

execution each time also need 7, 8 seconds How can we optimize it? From the pure SQL point of view is no problem, go index, rows value is not small, if the speed is very slow, you can see from 3 aspects of 1:INNODB parameters have been optimized, such as InnoDBbufferpoor_size such as 2:qcache hit rate. According to your appeal question, an hour this statement

For beginners, the veteran don't throw bricks Writing SQL statements has always been a relatively curious thing, written without a good error-checking mechanism, can only be run to find errors, especially the associated table more up, thoughts will inevitably be confused at last I do not know where to lose. The recent accidental discovery is not m$ did not provide a good fool interface to our lazy brother Lazy brothers use, but we ourselves ignore, th

The SQL SELECT into statement can be used to create a backup copy of the table.SELECT into statementThe SELECT INTO statement selects data from one table and then inserts the data into another table.The SELECT into

1.in when the query condition is ListSelectId="getmultimomentscommentscounts"Resulttype="int">SelectMoment_comment_count fromTbl_moment_commentcountwhereMidinchforeachitem="Item"index="Index"collection="List"open="("Separator=","Close=")">#{item}foreach> Select>.1 if the type of the parameter is list, then when used, the collection property must be specified as a list select id= "findbyidsmap" resultmap

Label:Youdao Written Questions: Server Monitoring table Server_status, when the server state occurs server_status changes in the data table will be inserted a record, state 0 indicates that the shutdown 1 is normal, SQL query Server A's downtime start time and end time, There is a status record for more than one server in the table. svr_id Svr_name Status_time STATUS 1 A 2013-10-31 00:00:00

Label:The SELECT into statement copies the data from one table and then inserts the data into another new table.SQL SELECT into syntaxWe can copy all the columns into the new table:SELECT * intonewtable[InExternaldb] Fromtable1; Or just copy the columns you want into the new table:SELECTcolumn_name (s)Intonewtable[InExternaldb] Fromtable1;

Label:If the Select section contains columns that are not required, this forces DB2 to go to the data page to get the specific columns requested, which requires more I/O operations. In addition, if you sort this unwanted column, you need to create and pass a larger sort file, which will make sorting more expensive.If more than one table is involved in a query, specifying extra columns also affects which joins are selected by the Optimization tool. Cur

Does the PHP SELECT statement need to use preprocessing to prevent SQL injection? Reply content: Does the PHP SELECT statement need to use preprocessing to prevent SQL injection? Some things you should know about

ArticleDirectory Summary: During this period of optimization, it is found that a statement has been executed for a long time and is very inefficient. The statement is as follows: Select ID, field015, field016, field017, field001, field020, field010, field014, field011, field013, field004, field018,Field005, field007, field003, Null , Reque

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