This page contains direct links to SQL tutorials and reference articles for beginners.
Tutorials
- SQL Tutorial for Beginners
- SQL Joins Tutorial
- SQL Transactions Tutorial
- Database Tutorial
- Basic SQL Queries (examples)
Data Definition Language (DDL)
Data Definition Language (DDL) is a subset of SQL that deals with creating and maintaining database objects such as tables, views, stored procedures, etc.
The actual syntax can vary quite widely between RDBMSs, but the articles listed here do their best to cover the commonly used features in most of the major RDBMSs.
Common SQL Statements:
- SQL
CREATE TABLEfor Beginners - SQL
ALTER TABLEfor Beginners - SQL
DROP COLUMNfor Beginners - SQL
DROP TABLEfor Beginners
Common tasks:
- Create a Relationship in SQL
- Add a Column to a Table in SQL
- How to Rename a Column in SQL
- How to Rename a Table in SQL
Data Manipulation Language (DML)
Data Manipulation Language (DML) is the part of SQL that deals with reading, writing, and updating data.
These are sometimes separated into “read DML” vs “write DML”, in order to distinguish between those statements that simply read the data and those that write, update, or delete data. Some also refer to the “read DML” statements as DQL for Data Query Language.
Most of these statements work in a similar way across most of the major RDBMSs for most of the commonly performed tasks. However, there can be differences in some cases, depending on the task being performed.
- SQL
SELECTfor Beginners - SQL
ORDER BYClause for Beginners - SQL
GROUP BYClause for Beginners - SQL
HAVINGClause for Beginners - SQL
DELETEfor Beginners - SQL
UPDATEfor Beginners - SQL
INSERTfor Beginners
Aggregate Functions
Aggregate functions return a single result row based on groups of rows, rather than on single rows. They can appear in SELECT lists and in ORDER BY and HAVING clauses. They are often used with the GROUP BY clause in a SELECT statement.
- SQL
AVG()for Beginners - SQL
COUNT()for Beginners - SQL
MAX()for Beginners - SQL
MIN()for Beginners - SQL
SUM()for Beginners
SQL Operators
In SQL, an operator is a special character or keyword specifying an action that is performed on one or more expressions.
Comparison Operators
- SQL Equals (
=) Operator for Beginners - SQL Less Than (
<) Operator for Beginners - SQL Less Than or Equal To (
<=) Operator for Beginners - SQL Not Equal To (
!=) Operator for Beginners
Logical Operators
- SQL
ANDOperator for Beginners - SQL
BETWEENOperator for Beginners - SQL
EXISTSOperator for Beginners - SQL
INOperator for Beginners - SQL
LIKEOperator for Beginners - SQL
NOTOperator for Beginners - SQL
OROperator for Beginners
Set Operators
- SQL
EXCEPTOperator (SQL Server) - SQL
INTERSECTOperator (SQL Server) - SQL
UNIONClause for Beginners
SQL Operator Reference
- SQL Operators (full list)
- 12 Commonly Used Operators in SQL