Query data in columns c1, c2 from a table
SELECT c1, c2 FROM t;
Query all rows and columns from a table
SELECT * FROM t;
Query data and filter rows with a condition
SELECT c1, c2 FROM t
WHERE condition;
Query distinct rows from a table
SELECT DISTINCT c1 FROM t
WHERE condition;
Sort the result set in ascending or descending order
SELECT c1, c2 FROM t
ORDER BY c1 ASC [DESC];
Skip offset of rows and return the next n rows
SELECT c1, c2 FROM t
ORDER BY c1
LIMIT n OFFSET offset;
Group rows using an aggregate function
SELECT c1, aggregate(c2)
FROM t
GROUP BY c1;
Filter groups using HAVING clause
SELECT c1, aggregate(c2)
FROM t
GROUP BY c1
HAVING condition;
Inner join t1 and t2
SELECT c1, c2
FROM t1
INNER JOIN t2 ON condition;
Left join t1 and t1
SELECT c1, c2
FROM t1
LEFT JOIN t2 ON condition;
Right join t1 and t2
SELECT c1, c2
FROM t1
RIGHT JOIN t2 ON condition;
Perform full outer join
SELECT c1, c2
FROM t1
FULL OUTER JOIN t2 ON condition;
Produce a Cartesian product of rows in tables
SELECT c1, c2
FROM t1
CROSS JOIN t2;
Another way to perform cross join
SELECT c1, c2
FROM t1, t2;
Join t1 to itself using INNER JOIN clause
SELECT c1, c2
FROM t1 A
INNER JOIN t1 B ON condition;
Combine rows from two queries
SELECT c1, c2 FROM t1
UNION [ALL]
SELECT c1, c2 FROM t2;
Return the intersection of two queries
SELECT c1, c2 FROM t1
INTERSECT
SELECT c1, c2 FROM t2;
Subtract a result set from another result set
SELECT c1, c2 FROM t1
MINUS
SELECT c1, c2 FROM t2;
Query rows using pattern matching %, _
SELECT c1, c2 FROM t1
WHERE c1 [NOT] LIKE pattern;
Query rows in a list
SELECT c1, c2 FROM t
WHERE c1 [NOT] IN value_list;
Query rows between two values
SELECT c1, c2 FROM t
WHERE c1 BETWEEN low AND high;
Check if values in a table is NULL or not
SELECT c1, c2 FROM t
WHERE c1 IS [NOT] NULL;
Create a new table with three columns
CREATE TABLE t (
id INT PRIMARY KEY,
name VARCHAR NOT NULL,
price INT DEFAULT 0
);
Delete the table from the database
DROP TABLE t ;
Add a new column to the table
ALTER TABLE t ADD column;
Drop column c from the table
ALTER TABLE t DROP COLUMN c ;
Add a constraint
ALTER TABLE t ADD constraint;
Drop a constraint
ALTER TABLE t DROP constraint;
Rename a table from t1 to t2
ALTER TABLE t1 RENAME TO t2;
Rename column c1 to c2
ALTER TABLE t1 RENAME c1 TO c2 ;
Remove all data in a table
TRUNCATE TABLE t;
Set c1 and c2 as a primary key
CREATE TABLE t(
c1 INT, c2 INT, c3 VARCHAR,
PRIMARY KEY (c1,c2)
);
Set c2 column as a foreign key
CREATE TABLE t1(
c1 INT PRIMARY KEY,
c2 INT,
FOREIGN KEY (c2) REFERENCES t2(c2)
);
Make the values in c1 and c2 unique
CREATE TABLE t(
c1 INT, c1 INT,
UNIQUE(c2,c3)
);
Ensure c1 > 0 and values in c1 >= c2
CREATE TABLE t(
c1 INT, c2 INT,
CHECK(c1> 0 AND c1 >= c2)
);
Set values in c2 column not NULL
CREATE TABLE t(
c1 INT PRIMARY KEY,
c2 VARCHAR NOT NULL
);
Insert one row into a table
INSERT INTO t(column_list)
VALUES(value_list);
Insert multiple rows into a table
INSERT INTO t(column_list)
VALUES (value_list),
(value_list), …;
Insert rows from t2 into t1
INSERT INTO t1(column_list)
SELECT column_list
FROM t2;
Update new value in the column c1 for all rows
UPDATE t
SET c1 = new_value;
Update values in the column c1, c2 that match the condition
UPDATE t
SET c1 = new_value,
c2 = new_value
WHERE condition;
Delete all data in a table
DELETE FROM t;
Delete subset of rows in a table
DELETE FROM t
WHERE condition;
Create a new view that consists of c1 and c2
CREATE VIEW v(c1,c2)
AS
SELECT c1, c2
FROM t;
Create a new view with check option
CREATE VIEW v(c1,c2)
AS
SELECT c1, c2
FROM t;
WITH [CASCADED | LOCAL] CHECK OPTION;
Create a recursive view
CREATE RECURSIVE VIEW v
AS
select-statement -- anchor part
UNION [ALL]
select-statement; -- recursive part
Create a temporary view
CREATE TEMPORARY VIEW v
AS
SELECT c1, c2
FROM t;
Delete a view
DROP VIEW view_name;
Create an index on c1 and c2 of the t table
CREATE INDEX idx_name
ON t(c1,c2);
Create a unique index on c3, c4 of the t table
CREATE UNIQUE INDEX idx_name
ON t(c3,c4)
Drop an index
DROP INDEX idx_name;
Create or modify a trigger
CREATE OR MODIFY TRIGGER trigger_name
WHEN EVENT
ON table_name TRIGGER_TYPE
EXECUTE stored_procedure;
WHEN
BEFORE – invoke before the event occurs
AFTER – invoke after the event occurs
EVENT
INSERT – invoke for INSERT
UPDATE – invoke for UPDATE
DELETE – invoke for DELETE
TRIGGER_TYPE
FOR EACH ROW
FOR EACH STATEMENT
Delete a specific trigger
DROP TRIGGER trigger_name;