MySQL is a popular relational database management system (RDBMS) that is widely used for web development. Here are some basics of MySQL:
- Database Creation:
- To create a new database, you use the
CREATE DATABASE
statement.sql CREATE DATABASE database_name;
- Table Creation:
- To create a table within a database, you use the
CREATE TABLE
statement.sql CREATE TABLE table_name ( column1 datatype, column2 datatype, ... );
- Data Types:
- MySQL supports various data types such as INT, VARCHAR, TEXT, DATE, etc. You need to specify the data type for each column when creating a table.
- Inserting Data:
- To insert data into a table, you use the
INSERT INTO
statement.sql INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ...);
- Selecting Data:
- To retrieve data from a table, you use the
SELECT
statement.sql SELECT column1, column2, ... FROM table_name WHERE condition;
- Updating Data:
- To update existing data in a table, you use the
UPDATE
statement.sql UPDATE table_name SET column1 = value1, column2 = value2 WHERE condition;
- Deleting Data:
- To delete data from a table, you use the
DELETE FROM
statement.sql DELETE FROM table_name WHERE condition;
- Constraints:
- Constraints are rules applied to a column to enforce data integrity. Common constraints include PRIMARY KEY, UNIQUE, NOT NULL, and FOREIGN KEY.
- Relationships:
- Tables can be related to each other using relationships. The most common types are one-to-one, one-to-many, and many-to-many relationships.
- Indexing:
- Indexes can be created on columns to improve the speed of data retrieval. Common types include UNIQUE indexes and PRIMARY KEY indexes.
- Joins:
- Joins are used to combine rows from two or more tables based on a related column between them. Common types include INNER JOIN, LEFT JOIN, and RIGHT JOIN.
- Aggregate Functions:
- MySQL provides aggregate functions like COUNT, SUM, AVG, MAX, and MIN for performing calculations on sets of values.
- Group By:
- The
GROUP BY
clause is used with aggregate functions to group the result set by one or more columns.
- The
- Order By:
- The
ORDER BY
clause is used to sort the result set based
- The
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