mysql query order by

The MySQL order BY keyword is used to classify the data in the record.MySQL ORDER BY keyword classified by keywordThe ORDER BY keyword is used to classify the data in a record. Copy Code code as follows: SELECT column_name (s) From table_name ORDER BY co

When using MySQL sorting, you would expect to get a set of data in descending order, but using order by often gets not the desired result, so how can you use Group by and order by to get the desired data results?For example there is a reply sheet for a post, posts (ID, TID, subject, message, Dateline),ID is the autogro

media_id=15); # Time: 100814 13:37:02 # User@Host: root[root] @ localhost [] # Query_time: 10.394134 Lock_time: 0.000091 Rows_sent: 1 Rows_examined: 2374192 SET timestamp=1281764222; select count(distinct ad_code) as x from ad_visit_history where ad_code in (select ad_code from ad_list where media_id=15); # Time: 100814 13:37:16 # User@Host: root[root] @ localhost [] # Query_time: 4.608920 Lock_time: 0.000078 Rows_sent: 1 Rows_examined: 1260544 SET timestamp=1281764236; select count(*

Next I will use the users (Userid,username,password ...). Table (with Ibedovan Records) as an example, to explain the next several methods of efficiency problems: The code is as follows Copy Code 1.select * from the Users Order by rand () LIMIT 1 Execute the SQL statement, no response for a while, finally forced to manually stop execution, how to hurt people ah! Then I looked up the

true, Then the field in select must appear in group by, so it is obvious that the old new version of the problem.Official documentation here:A new function, Any_value (), is available so can used to forceMySQL to accept queries that it thinks should is rejected withOnly_full_group_by enabled.The function return value and type areThe same as the return value and type of its argument, but thefunction result is a checked for the only_full_group_by SQL mode.If you find that has only_full_group_by e

Link query and set query bitsCN.com Connection query and set query In the database query process, sometimes the data records in a table cannot meet the needs of developers or customers. For example, query the student's course se

| + -------- + ---------- + --------- + ------------ + --------- + 1 row in SET (0.00 Sec) 2.6.2 field Query CEO: view employee salary Mysql> select emp_name, emp_sal from EMP; The query result is as follows: + ---------- + --------- + | Emp_name | emp_sal | + ---------- + --------- + | Xiaotian | 4000 | | Red maple | 9000 | | Lih

"How does the Order by rand () in MySQL come into being?" Let's briefly talk about order by in MySQL today.case of several order byShangri-La CasinoAt first glance the problem seems a bit complicated, and we start with the simplest case.Use this table to illustrate: (10w row

order by default (from 1 to 9, from a to z)Use the "DESC" keyword to sort all data in descending order (from 9 to 1, from z to ):SELECT column_name (s)FROM table_nameOrder by column_name DESCMySQL Order By is classified By two columnsMost of the time, we need to classify data based on the two columns (or more columns) at the same time. When the specified number

repeated, all columns are the same (for example, the data in rows 5 and 6 in the following table is identical ).The maximum two (N) val values are grouped by name.Copy codeThe Code is as follows:/*The data is as follows:Name val memoA 2 a2 (the second value of)A 1 a1 -- the first value ofA 1 a1 -- the first value ofA 3 a3: The third value ofA 3 a3: The third value ofB 1 b1 -- the first value of BB 3 b3: The third value of BB 2 b2b2b2b2B 4 b4b4B 5 b5b5b5b5b5*/ Appendix: Studies on

Create the mysql_order_by_test data table according to the following table structure. We will use instance to tell you how to use MySQL order. Order by uid ASC Query data in the forward order of uid, that is, sort data in ascending orde