Database SQL statement summary, continuous update

Catalog

1 SQL sentence Database related operations

1.1 Create and open a database

1.2 Delete database

1.3 Edit the database

1.4 Query the database

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1 SQL sentence Database related operations

The goal is ：

Will use SQL Statement to create a new database 、 Use 、 edit 、 Delete 、 Close operation .

1.1 Create and open a database

New database

Grammar format	Basic usage create database < Database name >	Syntax format with parameters ： create database [if not exists] < Database name > [charset Character set ] [collate Sort rule ]
Reverberation
Parameter description		if not exists —— If the database does not exist, create , If it exists, it will not report an error ; charset Character set —— The default value is utf8mb4; collate Sort rule —— The default value is utf8mb4_0900_ai_ci;
Illustrate with examples	# Create a name student  The database of create database student;	# Create a name teacher The database of , Repeat the command without error create database if not exists teacher; # Create a name school The database of , Specify the character set and collation create database if not exists school charset utf8mb4 collate utf8_general_ci;
remarks	Repeated command input will report an error	Character set is the code made to be compatible with the characters of various countries , such as GB2312、GBK etc. , We use utf8;

Open database

Grammar format	Basic grammar use Database name
Reverberation
Parameter description
Illustrate with examples	# open student database use student;
remarks

1.2 Delete database

Grammar format	# Basic grammar drop database < Database name >	# Syntax with parameters drop database [if exists] < Database name >
Reverberation
Parameter description
Illustrate with examples	# Delete student database drop database student;	# Delete student database drop database if exists student;
remarks

1.3 Edit the database

Grammar format	alter database < Database name > [default character set Character set ] [default collate Sort rule ]
Reverberation
Parameter description
Illustrate with examples	# Create a name test The database of , The character set is gb2132 create database test charset gb2312; # modify test The specified character set is utf8mb4, The sorting rule is utf8mb4_general_ci; alter database test default character set utf8mb4 default collate utf8mb4_general_cli;
remarks	[default character set Character set ] You can also make mistakes [default charset Character set ]

1.4 Query the database

command	explain
show databases;	View all databases
select database();	View currently used databases
show create database Database name ;	View creation xxx The syntax of the database