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MySQL database query basics, simple query, conditional query, sorting query results
MySQL database query basics, simple query, conditional query, sorting query results
1. SELECT statement SELECT COL1, COL2, ....COLn FROM TABLE1, TABLE2, ....TABLEn
[WHERE CONDITIONS] -- Query conditions
[GROUP BY GROUP_BY_LIST] -- Query result grouping
[HAVING CONDITIONS] -- Query conditions - statistical results as conditions
[ORDER BY ORDER_LIST[ASC|DESC] -- Query result sorting
2. Simple query
1. Query all rows and columns in the table
eg: Query all rows and columns in the player table
select user_qq,user_name,user_sex,user_birthday,user_mobile from users;
select * from users;
2. Query some columns of the table
eg: Query from the player table Player QQ and nickname
select user_qq,user_name from users;
3. Use of alias
eg: Query player QQ and nickname from the player table and display it as ' Player QQ' and 'player nickname'
select user_qq as 'player QQ',user_name as 'player nickname' from users;
select user_qq 'player QQ',user_name 'player nickname' from users;
4.DISTINCT keyword-eliminate duplicate rows in the result set
eg: Display QQ of players who participated in the game, and require players who participated in multiple games not to display QQ repeatedly
select distinct user_qq from scores;
5.LIMIT keyword-specify the display range of the data in the result set
eg: Display the 3rd to 5th data in the player table
select * from users limit 2,3;
select*from users limit 3 ---Only display the first three pieces of data
三.Conditional query
1. Ordinary condition query
Syntax: SELECT COL_LIST FROM TABLE_NAME [WHERE CONDITION_EXPRESSION]
eg1: Query the player information with QQ number 12301
select * from users where user_qq =12301;
eg2: Query data with scores greater than 2500
select *from scores where score>2500;
<> --- --Not equal to >= -----Greater than or equal to <= -----Less than or equal to
eg3: Query the score information of the game number 1 and the score is greater than 4000 points
select * from scores where gno=1 and score>4000;
Logical operators: and-- and
or-- or
#eg4: Query the score information of game numbers 1 and 2select * from scores where gno=1 or gno=2;2. Fuzzy queryeg1: Query scores with scores between 2500 (inclusive) and 3000 (inclusive)select *from scores where score>=2500 and score<=3000;select * from scores where score between 2500 and 3000;eg2: Query score information where score is not between 2500 (inclusive) and 3000 (inclusive)select * from scores where score not between 2500 and 3000;eg3: Query players born from January 1, 1987 to July 31, 1992select * from users where user_birthday between '1987-01-01' and '1992-0731';
Wildcard: '_' One character Branch like 'L_' Any length Route_Code Like 'AMS-%' [] Within the specified range Airbusno Like 'AB0[1-5 ] ' [^^] Not in parentheses, Airbusno Like' Ab0 [^] ' Eg4: Query all the player information of all the surnames of the Sun
## Select * from users where user_name like 'Sun%';
eg5: Query the information of all players whose surname is not Sun
select * from users where user_name not like 'Sun%';
3. Query empty Value operator
eg: Query the information of players whose birthday is null
select * from users where use_birthday is null;
eg: Query the players whose birthday is not NULL Information
select * from users where user_birthday is not null;
Four pairs of query results sorting
1. Sort the specified column (sort by , sorting method)
Syntax: SELECT CLO_LIST FROM TABLE_NAME ORDER BY ORDER_BY_LIST [ASC/DESC]
Example: Query all score information numbered 1 in the score table, and sort by score in ascending order
select *from scores where gno=1 order by score asc.
Example: Query all score information numbered 1 in the score table, and sort by score in descending order
select * from score where gno=1 order by score desc.
2. Sort multiple columns (sorting basis, sorting method, priority)
Example: Query all information in the score table , and sort in ascending order of game number and descending order of score
select * from scores order by gno asc, score desc
The above is the detailed content of MySQL database query basics, simple query, conditional query, sorting query results. For more information, please follow other related articles on the PHP Chinese website!
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