RESOURCES - SQL
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SQL stands for Structured Query Language.
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Other useful acronyms:
- DML: Data Manipulation Language, refers to the structure, schema of the database (CREATE, ALTER, TRUNCATE, RENAME and DROP operations)
- DDL: Data Definition Language, allows to manage and manipulate data in the database (SELECT, UPDATE, DELETE and INSERT operations)
- DCL: Data Control Language, deals with user access control to the database, rights and permissions (REVOKE, GRANT operations)
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Reminder of SQL JOINS:
-- LEFT JOIN:
SELECT [fields]
FROM [Table A] A
LEFT JOIN [Table B] B
ON A.key_field = B.key_field;
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-- LEFT JOIN with null key value on B:
SELECT [fields]
FROM [Table A] A
LEFT JOIN [Table B] B
ON A.key_field = B.key_field
WHERE B.key_field is NULL;
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-- FULL OUTER JOIN:
SELECT [fields]
FROM [Table A] A
FULL OUTER JOIN [Table B] B
ON A.key_field = B.key_field;
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-- RIGHT JOIN:
SELECT [fields]
FROM [Table A] A
RIGHT JOIN [Table B] B
ON A.key_field = B.key_field;
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-- RIGHT JOIN with null key value on A:
SELECT [fields]
FROM [Table A] A
RIGHT JOIN [Table B] B
ON A.key_field = B.key_field
WHERE A.key_field is NULL;
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-- FULL OUTER JOIN with null key value on A or B:
SELECT [fields]
FROM [Table A] A
FULL OUTER JOIN [Table B] B
ON A.key_field = B.key_field
WHERE A.key_field is NULL
OR B.key_field is NULL;
-- INNER JOIN:
SELECT [fields]
FROM [Table A] A
INNER JOIN [Table B] B
ON A.key_field = B.key_field;
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