A quick SQL cheat sheet of all relevant SQL queries and examples with quick guide how to use them, such as: Finding Data Queries, Data Modification Queries, Reporting Queries, Join Queries, View Queries, Altering Table Queries and Creating Table Query.

1. Finding Data Queries

  • SELECT: used to fetch data from a database table
SELECT * FROM table_name;

  • DISTINCT: filters away duplicate values and returns rows of specified column
SELECT DISTINCT column_name;

  • WHERE: used to filter records/rows
SELECT column1, column2 FROM table_name WHERE condition;
SELECT * FROM table_name WHERE condition1 AND condition2;
SELECT * FROM table_name WHERE condition1 OR condition2;
SELECT * FROM table_name WHERE NOT condition;
SELECT * FROM table_name WHERE condition1 AND (condition2 OR condition3);
SELECT * FROM table_name WHERE EXISTS (SELECT column_name FROM table_name WHERE condition);

  • ORDER BY: used to sort the result-set in ascending or descending order
SELECT * FROM table_name ORDER BY column;
SELECT * FROM table_name ORDER BY column DESC;
SELECT * FROM table_name ORDER BY column1 ASC, column2 DESC;

  • SELECT TOP: used to specify the number of records to return from top of table. Not all database systems support SELECT TOP. The MySQL equivalent is the LIMIT clause

SELECT TOP number columns_names FROM table_name WHERE condition;
SELECT TOP percent columns_names FROM table_name WHERE condition;
SELECT column_names FROM table_name LIMIT offset, count;

  • LIKE: operator used in a WHERE clause to search for a specific pattern in a column
  • % (percent sign) is a wildcard character that represents zero, one, or multiple characters
  • _ (underscore) is a wildcard character that represents a single character
SELECT column_names FROM table_name WHERE column_name LIKE pattern;

-- Like patterns
LIKE ‘a%’ (find any values that start with “a”)
LIKE ‘%a’ (find any values that end with “a”)
LIKE ‘%or%’ (find any values that have “or” in any position)
LIKE ‘_r%’ (find any values that have “r” in the second position)
LIKE ‘a_%_%’ (find any values that start with “a” and are at least 3 characters in length)
LIKE ‘[a-c]%’ (find any values starting with “a”, “b”, or “c”

  • IN: operator that allows you to specify multiple values in a WHERE clause essentially the IN operator is shorthand for multiple OR conditions
SELECT column_names FROM table_name WHERE column_name IN (value1, value2, …);
SELECT column_names FROM table_name WHERE column_name IN (SELECT STATEMENT);

  • BETWEEN: operator selects values within a given range inclusive
SELECT column_names FROM table_name WHERE column_name BETWEEN value1 AND value2;
SELECT * FROM Products WHERE (column_name BETWEEN value1 AND value2) AND NOT column_name2 IN (value3, value4);
SELECT * FROM Products WHERE column_name BETWEEN #01/07/1999# AND #03/12/1999#;

  • NULL: values in a field with no value
SELECT * FROM table_name WHERE column_name IS NULL;
SELECT * FROM table_name WHERE column_name IS NOT NULL;

  • AS: aliases are used to assign a temporary name to a table or column
SELECT column_name AS alias_name FROM table_name;
SELECT column_name FROM table_name AS alias_name;
SELECT column_name AS alias_name1, column_name2 AS alias_name2;
SELECT column_name1, column_name2 + ‘, ‘ + column_name3 AS alias_name;

  • UNION: set operator used to combine the result-set of two or more SELECT statements
  • The columns must have similar data types
  • The columns in each SELECT statement must also be in the same order
  • Each SELECT statement within UNION must have the same number of columns
  • UNION operator only selects distinct values, UNION ALL will allow duplicates
SELECT columns_names FROM table1 UNION SELECT column_name FROM table2;

  • INTERSECT: set operator which is used to return the records that two SELECT statements have in common.
  • Generally used the same way as UNION above
SELECT columns_names FROM table1 INTERSECT SELECT column_name FROM table2;

  • EXCEPT: set operator used to return all the records in the first SELECT statement that are not found in the second SELECT statement
  • Generally used the same way as UNION above
SELECT columns_names FROM table1 EXCEPT SELECT column_name FROM table2;

  • ANY|ALL: operator used to check subquery conditions used within a WHERE or HAVING clauses
  • The ANY operator returns true if any subquery values meet the condition
  • The ALL operator returns true if all subquery values meet the condition
SELECT columns_names FROM table1 WHERE column_name operator (ANY|ALL)
(SELECT column_name FROM table_name WHERE condition);

  • GROUP BY: statement often used with aggregate functions (COUNT, MAX, MIN, SUM, AVG) to group the result-set by one or more columns
SELECT column_name1, COUNT(column_name2) FROM table_name WHERE condition GROUP BY column_name1 ORDER BY COUNT(column_name2) DESC;

  • HAVING: this clause was added to SQL because the WHERE keyword could not be used with aggregate functions
SELECT COUNT(column_name1), column_name2 FROM table GROUP BY column_name2 HAVING COUNT(column_name1) > 5;

  • WITH: often used for retrieving hierarchical data or re-using temp result set several times in a query. Also referred to as "Common Table Expression"
WITH RECURSIVE cte AS (
  SELECT c0.* FROM categories AS c0 WHERE id = 1 # Starting point
  UNION ALL
  SELECT c1.* FROM categories AS c1 JOIN cte ON c1.parent_category_id = cte.id
)
SELECT *
FROM cte

2. Data Modification Queries

  • INSERT INTO: used to insert new records/rows in a table
INSERT INTO table_name (column1, column2) VALUES (value1, value2);
INSERT INTO table_name VALUES (value1, value2 …);

  • UPDATE: used to modify the existing records in a table
UPDATE table_name SET column1 = value1, column2 = value2 WHERE condition;
UPDATE table_name SET column_name = value;

  • DELETE: used to delete existing records/rows in a table
DELETE FROM table_name WHERE condition;
DELETE * FROM table_name;

3. Reporting Queries

  • COUNT: returns the # of occurrences
SELECT COUNT (DISTINCT column_name);

  • MIN() and MAX(): returns the smallest/largest value of the selected column
SELECT MIN (column_names) FROM table_name WHERE condition;
SELECT MAX (column_names) FROM table_name WHERE condition;

  • AVG(): returns the average value of a numeric column
SELECT AVG (column_name) FROM table_name WHERE condition;

  • SUM(): returns the total sum of a numeric column
SELECT SUM (column_name) FROM table_name WHERE condition;

4. Join Queries

  • INNER JOIN: returns records that have matching value in both tables
SELECT column_names FROM table1 INNER JOIN table2 ON table1.column_name=table2.column_name;

SELECT table1.column_name1, table2.column_name2, table3.column_name3 
FROM ((table1 INNER JOIN table2 ON relationship) 
INNER JOIN table3 ON relationship);

  • LEFT (OUTER) JOIN: returns all records from the left table (table1), and the matched records from the right table (table2)
SELECT column_names FROM table1 
LEFT JOIN table2 ON table1.column_name=table2.column_name;

  • RIGHT (OUTER) JOIN: returns all records from the right table (table2), and the matched records from the left table (table1)
SELECT column_names FROM table1 
RIGHT JOIN table2 ON table1.column_name=table2.column_name;

  • FULL (OUTER) JOIN: returns all records when there is a match in either left or right table
SELECT column_names FROM table1 
FULL OUTER JOIN table2 ON table1.column_name=table2.column_name;

  • Self JOIN: a regular join, but the table is joined with itself
SELECT column_names FROM table1 T1, table1 T2 
WHERE condition;

5. View Queries

  • CREATE: create a view
CREATE VIEW view_name AS 
  SELECT column1, column2 FROM table_name
  WHERE condition;

  • SELECT: retrieve a view
SELECT * FROM view_name;

  • DROP: drop a view
DROP VIEW view_name;

6. Altering Table Queries

  • ADD: add a column
ALTER TABLE table_name ADD column_name column_definition;

  • MODIFY: change data type of column
ALTER TABLE table_name MODIFY column_name column_type;

  • DROP: delete a column
ALTER TABLE table_name DROP COLUMN column_name;

7. Creating Table Query

  • CREATE: create a table
CREATE TABLE table_name (
column1 datatype,
column2 datatype,
column3 datatype,
column4 datatype,
);

Originally posted at: github.com by @enochtangg