Mysql uses median to temporarily store values

Mysql uses the median to temporarily store the value. When querying data, mysql sometimes uses the following statement to find a value. At this time, you may consider how to store this value, there are two methods to achieve the goal: 1. Use custom values. II. Use an intermediate table. The following describes how to call these two methods: www.2cto.com 1. how to save a value of a table to a custom variable using memory SQL code # define @ amax_price as a constant value mysql> set @ amax_price = (select max (FScoreCount) from Tbl_User); Query OK, 0 rows affected (0.00 sec) mysql> select * from Tbl_User where FScoreCount = @ amax_price; + --------- + ----------- + ------- + ------ + ------------- + ------------ + -------------- + -------- + --------- + ----------- + ------------ -- + ------- + --------- + Response + ---------- + response + ------------ --------- + response + ------- + | FUserId | FQQ | FNick | FPwd | FScoreCount | FVoteCount | FInviteCount | FBType | FLType | FEnable | FValue1 | FValue2 | FValue3 | FValue4 | FValue 5 | FValue6 | FTime | FDate | FIp | FLastLoginT ime | FLastLoginDate | FMemo | + --------- + ------- + ------ + ----- -------- + ------------ + Certificate + -------- + --------- + certificate + ------- + --------- + certificate + ---------- + certificate + ------------ ----------- + certificate + ------- + | 1 | 455342107 | 22 | 0 | 2 | 0 | 0 | 0 | 1 | 0 | 2011-08-15_3 | 2011-0 8-10_2 | 10:02:40 | 2011-08-10 | 192.168.1.34 | 14:30:18 | 20 11-08-16 | + --------- + ----------- + ------- + ------ + upper + ------------ + -------------- + -------- + --------- + --------- + --------------------- + ------------ + -------------- + ------------ --------- + ---------------- + ------- + 2. how to save a value of a table to the SQL code of the temporary table # locate all values in the Tbl_User table mysql> select FQQ, FScoreCount from Tbl_User; + ----------- + ---------- --- + | FQQ | FScoreCount | + ----------- + | 455342107 | 22 | 24222 | 0 | 345333 | 5 | 664444 | 5 | 234324 | 0 | 137543511 | 5 | 519422206 | 5 | 234222 | 0 | 14234 | 5 | 1242354 | 5 | 111565 | 5 | 342323 | 0 | 234322 | 0 | 543244 | 0 | + ----------- + ------------- + 14 rows in set (0.00 sec) # store the maximum value on the temporary table tmp mysql> create table tmp select max (FScoreCount) as max_s Core from Tbl_User; Query OK, 1 row affected (0.05 sec) Records: 1 Duplicates: 0 Warnings: 0 # locate the temporary table structure mysql> select * from tmp; + ----------- + | max_score | + ----------- + | 22 | + ----------- + 1 row in set (0.00 sec) mysql> show tables; + comment + | tables_in_db_nissansunny_20151108 | + ---------------------------------- + | Tbl_Code | Tbl_Comment | Tbl_File | Tbl_Invite History | Tbl_LotteryCount | statistics | Tbl_QQshow | Tbl_Score | statistics | Tbl_User | Tbl_UserAward | Tbl_UserProfile | tmp | + statistics + 14 rows in set (0.00 sec) the two methods are different: the custom variables use the memory, and the temporary tables use the database space .. Haha, we recommend that you use a temporary table for a large data volume...