"MySQL must know" study notes _1

# Select Database

Use MySQL

# return to the list of available databases

SHOW DATABASES

# Returns the tables available in the current database

SHOW TABLES

# return table columns

SHOW COLUMNS from DB

# Show creation statements for a specific database

SHOW CREATE DATABASE MySQL

# Displays extensive server status information

SHOW STATUS

# Show security permissions for authorized users

SHOW GRANTS

Multiple SQL statements must be separated by semicolons.

SQL statements are case-insensitive and habitually capitalized.

Retrieve different rows with DISTINCT, returning only different values.

Limit result, limit clause

LIMIT 5 returns no more than 5 rows.

LIMIT 3,4 4 lines starting from line 3

LIMIT 4 OFFSET 3 (results ibid.) "MySQL5 support Later"

ORDER BY clause ordering

Desc/asc specifying the sort direction

the WHERE clause, where theORDER by is located .

Operator	Description
=	Equals
<>	Not equal to
!=	Not equal to
<	Less than
<=	Less than or equal
>	Greater than
>=	Greater than or equal
Between	Between a specified two values

NULL No value

The WHERE * * is null check field has no null value.

and OR operators.

The in operator is used to specify a range of criteria, and multiple legal values are separated by commas.

The not negation operator, which supports negation of in ,between , and EXISTS clauses.