This document summarizes MySQL queries for data definition language (DDL) and data manipulation language (DML). For DDL, it describes commands to create, alter, drop databases and tables. For tables, it covers adding, modifying and dropping columns and constraints. For DML, it outlines commands to insert, select, update and delete data from tables based on conditions. Identifiers for database, table, column and constraint names follow rules where the first character is alphabetic and subsequent characters can include numbers and underscores.

1. MySQL Queries
DDL (Data definition language)
DATABASE
TABLE
Create database CREATE DATABASE<database_name>;
Show databases list SHOW DATABASES;
Select/Use database USE<database_name>;
Delete/Drop database DROP DATABASE<database_name>;
Create table CREATE TABLE <table_name>
(< column_name1><datatype> [<constraint>],
< column_name2><datatype>
[<constraint>],…);
Show tables list SHOW TABLES;
Describe table(table structure) DESCRIBE<table_name>;
Delete/Drop table DROP TABLE<table_name>;
Rename table ALTER TABLE<old_table_name>
RENAME TO<new_table_name>;
Add a column ALTER TABLE <table name>
ADD <new_column_name><datatype>
[<constraint>];
Rename a column ALTER TABLE <table name>
CHANGE
<old_column_name><new_column_name><datat
ype>[<constraint>];
Delete a column ALTER TABLE <table name>
DROP <column_name>;
Modify datatype or
size
ALTER TABLE <table name>
MODIFY <column_name><datatype>
[<constraint>];
COLUMN
CONSTRAINTS
Constrain
ts
Add constraint Drop constraint
Not null ALTER TABLE <table name>
MODIFY <column_name><datatype>NOT
NULL;
ALTER TABLE <table name>
MODIFY
<column_name><datatype>NUL

2. DML (Data Manipulation language)
INSERT
Insert into all columns INSERT INTO <table_name>
VALUES(<column1_value>,< column2_value>,……);
Insert into specific columns INSERTINTO<table_name> (<column1>, <column2>,…)
VALUES(<column1_value>, <column2_value>,……);
SELECT
Select all data (all rows all columns –
full table)
SELECT *
FROM<table_name>;
Select specific columns SELECT<column1, column2,….>
FROM <table_name>;
Select all data based on condition SELECT *
FROM<table_name> WHERE <condition>;
Select data in ascending/descending
order
SELECT *
FROM<table_name>
ORDER BY <column1><ascending/descending>;
UPDATE
Update values which satisfy condition UPDATE<table_name>
SET<column_name>=<new_value>;
Update all values of a specific
column(same values for a particular
column)
UPDATE<table_name>
SET<column_name>=<new_value>
WHERE<condition>;
L;
Unique ALTER TABLE <table name>
ADD CONSTRAINT <constraint_name>
UNIQUE (<column_name>);
ALTER TABLE <table name>
DROP INDEX
<constraint_name>;
Check ALTER TABLE <table name>
ADD CONSTRAINT <constraint_name>
CHECK (<column_name><condition>);
ALTER TABLE <table name>
DROP CHECK
<constraint_name>;
Primary
key
ALTER TABLE <table name>
MODIFY <column_name><datatype>
PRIMARY KEY;
ALTER TABLE <table name>
DROP PRIMARY KEY;
Default ALTER TABLE <table name>
ALTER <column_name>
SET DEFAULT<value>;
ALTER TABLE <table name>
ALTER <column_name> DROP
DEFAULT;
Foreign key ALTER TABLE <table name>
ADD CONSTRAINT <constraint_name>
FOREIGN KEY (<column_name>)
REFERENCES <table
name1>(<column_name>);
ALTER TABLE <table name>
DROP FOREIGN KEY
<constraint_name>;

3. DELETE
Delete specific rows based on
condition
DELETE
FROM <table_name>
WHERE <condition>;
Clear all data of a table(delete all
rows)
DELETE
FROM <table_name>;
Identifiers-
An Identifier is essentially a name of a database_name, table_name, column_name or
constraint_name.
Rules-
1. First letter must be alphabet (a-z, A-Z).
2. Second and other letters can be numbers (0-9), alphabet (a-z, A-Z) and _ (underscore).
3. Must not be a keyword.