ALTER TABLE table_name ADD column datatype;ALTER TABLE lets you add columns to a table in a database.
SELECT column_name(s)
FROM table_name
WHERE column_1 = value_1
AND column_2 = value_2;AND is an operator that combines two conditions. Both conditions must be true for the row to be included in the result set.
SELECT column_name AS 'Alias'
FROM table_name;AS is a keyword in SQL that allows you to rename a column or table using an alias.
SELECT AVG(column_name)
FROM table_name;
AVG() is an aggregate function that returns the average value for a numeric column.
SELECT column_name(s)
FROM table_name
WHERE column_name BETWEEN value_1 AND value_2;The BETWEEN operator is used to filter the result set within a certain range. The values can be numbers, text or dates.
SELECT COUNT(column_name)
FROM table_name;COUNT() is a function that takes the name of a column as an argument and counts the number of rows where the column is not NULL.
CREATE TABLE table_name (column_1 datatype, column_2 datatype, column_3 datatype);CREATE TABLE creates a new table in the database. It allows you to specify the name of the table and the name of each column in the table.
DELETE FROM table_name WHERE some_column = some_value;DELETE statements are used to remove rows from a table.
SELECT COUNT(*)
FROM table_name
GROUP BY column_name;GROUP BY is a clause in SQL that is only used with aggregate functions. It is used in collaboration with the SELECT statement to arrange identical data into groups.
SELECT column_name(s) FROM table_1
JOIN table_2
ON table_1.column_name = table_2.column_name;An inner join will combine rows from different tables if the join condition is true.
INSERT INTO table_name (column_1, column_2, column_3) VALUES (value_1, 'value_2', value_3);INSERT statements are used to add a new row to a table.
SELECT column_name(s)
FROM table_name
WHERE column_name LIKE pattern;LIKE is a special operator used with the WHERE clause to search for a specific pattern in a column.
SELECT column_name(s)
FROM table_name
LIMIT number;LIMIT is a clause that lets you specify the maximum number of rows the result set will have.
SELECT MAX(column_name)
FROM table_name;MAX() is a function that takes the name of a column as an argument and returns the largest value in that column.
SELECT MIN(column_name)
FROM table_name;MIN() is a function that takes the name of a column as an argument and returns the smallest value in that column.
SELECT column_name
FROM table_name
WHERE column_name = value_1
OR column_name = value_2;OR is an operator that filters the result set to only include rows where either condition is true.
SELECT column_name
FROM table_name
ORDER BY column_name ASC|DESC;ORDER BY is a clause that indicates you want to sort the result set by a particular column either alphabetically or numerically.
SELECT column_name(s) FROM table_1
LEFT JOIN table_2
ON table_1.column_name = table_2.column_name;An outer join will combine rows from different tables even if the the join condition is not met. Every row in the left table is returned in the result set, and if the join condition is not met, then NULL values are used to fill in the columns from the right table.
SELECT ROUND(column_name, integer)
FROM table_name;ROUND() is a function that takes a column name and an integer as an argument. It rounds the values in the column to the number of decimal places specified by the integer.
SELECT column_name FROM table_name;SELECT statements are used to fetch data from a database. Every query will begin with SELECT.
SELECT DISTINCT column_name FROM table_name;SELECT DISTINCT specifies that the statement is going to be a query that returns unique values in the specified column(s).
SELECT SUM(column_name)
FROM table_name;SUM() is a function that takes the name of a column as an argument and returns the sum of all the values in that column.
UPDATE table_name
SET some_column = some_value
WHERE some_column = some_value;UPDATE statments allow you to edit rows in a table.
SELECT column_name(s)
FROM table_name
WHERE column_name operator value;WHERE is a clause that indicates you want to filter the result set to include only rows where the following condition is true.
01. Import ".sql" file from command prompt:
SOURCE C://database.sql;02. MySQL Performance Queries:
OPTIMIZE TABLE table_name;
--Displays description of the table
SHOW TABLE STATUS;
DESC table_name;
SHOW VARIABLES;
SHOW STATUS;
SHOW GLOBAL STATUS;
SHOW TABLES FROM INFORMATION_SCHEMA;
EXPLAIN SELECT * FROM table_name
SHOW TABLE STATUS FROM database_name;
--Shows you which threads are running
SHOW FULL PROCESSLIST;
--IP Address of the Mysql Host
SHOW VARIABLES WHERE Variable_name = 'hostname'; 04. Table Related Queries:
SELECT max(RIGHT(`field_name`,4)) FROM `table_name`;
-- Converts to upper case
SELECT UCASE(column_name) FROM table_name;
--Select nearest value
SELECT * FROM TABLE ORDER BY ABS(VALUE - $MYVALUE) LIMIT 1
SELECT sentence, wordcount(sentence) as "Words" from test;
--Useful in pagination
SELECT * FROM table_name ORDER BY field_name LIMIT 5 OFFSET 5;
--Find duplicate entries
SELECT *, COUNT(field_name) FROM table_name GROUP BY field_name HAVING ( COUNT(field_name) > 1 )
ALTER TABLE table_name AUTO_INCREMENT =1
ALTER TABLE `table_name` DROP PRIMARY KEY
ALTER TABLE `table_name` ENGINE = InnoDB
ALTER TABLE table_name CHANGE `id` `id` INT( 11 ) NOT NULL AUTO_INCREMENT
ALTER TABLE `table_name` ADD `id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY FIRST ;
ALTER TABLE table_name ADD column_name datatype AFTER column_name
ALTER TABLE table_name DROP COLUMN column_name
ALTER TABLE table_name MODIFY column_name datatype
ALTER TABLE table_name CHANGE oldname newname datatype
RENAME TABLE `table_name_old` TO `table_name_new`
--Update particular character
UPDATE mytable SET city = REPLACE(city, 'ï', 'i')
--Swaping field value
UPDATE swap_test SET x=y, y=@temp where @temp:=x;
--COPYING
UPDATE table_name SET field_name1=field_name2;
UPDATE table_name SET field_name = UPPER(field_name)
TRUNCATE TABLE table_name;
DROP TABLE table_name;05. Date and time:
SHOW VARIABLE LIKE '%time_zone%';
--Current timestamp
SELECT NOW();
--Current day
SELECT DAYNAME(NOW());
--Subtract time
SELECT SUBTIME('1:30:00', '00:15:00');
--Date Format
SELECT DATE_FORMAT(NOW(), '%W, %D of %M, %Y');
SELECT TIMEDIFF('2007-10-05 12:10:18','2007-10-05 16:14:59') AS length;
SELECT * FROM `table_name` WHERE DATE_FORMAT(field_name, "%Y-%m-%d") = '2010-01-01'"06. MySQL Miscellaneous Queries:
--Use to generate unique id
SELECT uuid();
--Get numeric values
SELECT * FROM `TABLENAME` WHERE `field` REGEXP '^-?[0-9]+$'
--w3resource.com
SELECT CONCAT('w3resource','.','com');
--bit datatype
CREATE TABLE table_bit (id SERIAL, a BIT(3), b BIT(8), c BIT(16));
--Enum datatype
CREATE TABLE table_enum (id SERIAL, status ENUM('Active', 'Deactive'));
--Get the length
SELECT CHAR_LENGTH(field_name) AS Length FROM `table_name`;
SELECT * FROM `table_name` WHERE LENGTH(field_name) < 10
--Copying the previous rows to the next rows
INSERT INTO table_name (`col1`, `col2`, `col3`, `...`, `coln`) SELECT `col1`, `col2`, `col3`, `...`, `coln` FROM table_name
SELECT COUNT(DISTINCT column) FROM table;
SELECT field_name, LEFT(field_name, 3), RIGHT(field_name, 3), MID(field_name, 2, 3) FROM `table_name`;
--Flow control with CASE
SELECT CASE WHEN a THEN 'true' ELSE 'false' END AS boolA, CASE WHEN b THEN 'true' ELSE 'false' END AS boolB FROM table_name;