Database management system:

Types:

Links:

SQL Basic Queries:

SELECT * FROM tableName; SELECT column1, column2 FROM tableName;  SELECT column1, column2 FROM tableName WHERE id=3;  SELECT * FROM tableName WHERE column1="column value"; SELECT column1 FROM tableName WHERE column1 IN (value1, value2,..);`// a coupleSELECT * FROM tableName WHERE id > 100 OR column1="column value"; SELECT LTRIM("    SQL data        ") AS column_name;  // Remove leading spaces from a stringSELECT RTRIM("    SQL data        ") AS column_name; // Remove trailing spaces from a string// patternsSELECT column1 FROM tableName WHERE column1 LIKE pattern;SELECT column1 FROM tableName WHERE column1 LIKE "%a%"; // have 'a' in itSELECT column1, column2 AS "new column name" FROM tableName;  SELECT column1, column2 FROM tableName AS tableAlias;SELECT column1, column2 FROM tableName WHERE columnName1 operator 'value';SELECT column1, column2 FROM tableName WHERE condition operator 'value' AND|OR condition operator 'value';SELECT column1(s) FROM tableName1 INNER JOIN tableName2 ON tableName1.column1=tableName2.column1;SELECT column1(s) FROM tableName1 LEFT JOIN tableName2 ON tableName1.column1=tableName2.column1;SELECT column1(s) FROM tableName1 RIGHT JOIN tableName2 ON tableName1.column1=tableName2.column1;SELECT column1(s) FROM tableName1 FULL JOIN tableName2 ON tableName1.column1=tableName2.column1;SELECT column1(s) FROM tableName WHERE column1 BETWEEN value1 AND value2;SELECT * INTO new_tableName [IN externaldatabase] FROM old_tableName;SELECT column1(s) INTO new_tableName [IN externaldatabase] FROM old_tableName;// clausesSELECT column1, column2 FROM tableName LIMIT 5;SELECT column1, column2 FROM tableName LIMIT 5 OFFSET 5;SELECT column1, column2 FROM tableName ORDER BY columnName1 [ASC|DESC];SELECT column1, column2 FROM tableName WHERE columnName1 operator 'value' ORDER BY column2 [ASC|DESC];SELECT column1, aggregate_function(column1) FROM tableName WHERE column1 operator value GROUP BY column1;SELECT column1 FROM tableName WHERE column1="value" GROUP BY column1 HAVING column1="value";// functionsSELECT ROUND(AVG(column1)) FROM tableName;SELECT COUNT(*) FROM tableName;SELECT COUNT(column1) FROM tableName;    SELECT SUM(column1) FROM tableName;SELECT AVG(column1) FROM tableName;SELECT MAX(column1) - MIN(column1) FROM tableName;SELECT DISTINCT column1, column2 FROM tableName;SELECT COUNT(column1) - COUNT(DISTINCT column1) AS newColumnName FROM tableName;SELECT TOP number|percent column1 FROM tableName;// insertINSERT INTO tableName VALUES (value1, value2, value3,....);INSERT INTO tableName (column1, column2) VALUES ('value1', 'value2');UPDATE tableName SET column1=NULL, column2='value' WHERE columnData=5;// deleteDELETE FROM tableName WHERE id=5;DELETE FROM tableName; // delete all rows from the entire tableDROP DATABASE database_name; // delete database completlyDROP DATABASE // drops all tablesDROP INDEX tableName.index_name (SQL Server);DROP INDEX index_name ON tableName (MS Access);DROP INDEX index_name (DB2/Oracle);ALTER TABLE tableName;DROP INDEX index_name (MySQL);DROP TABLEDROP TABLE tableName;// createCREATE DATABASE database_name;CREATE TABLE tableName(    id INTEGER PRIMARY KEY AUTOINCREMENT,    column2 TEXT NOT NULL,    column3 INTEGER NOT NULL);CREATE INDEX index_name ON tableName (column1);CREATE UNIQUE INDEX index_name ON tableName (column1);CREATE VIEW view_name AS SELECT column1(s) FROM tableName WHERE condition;// updateUPDATE tableName SET column1="value" WHERE column2="value" AND column3="value";// additional:TRUNCATE TABLE tableName;UNIONSELECT column1(s) FROM tableName1;UNION ALLSELECT column1(s) FROM tableName2;ALTER TABLE tableName ADD column1 datatype;ALTER TABLE tableName DROP COLUMN column1;IF EXISTS (SELECT * FROM tableName WHERE id = ?)BEGIN--do what needs to be done if existsENDELSEBEGIN--do what needs to be done if notEND