SQL data types define the type of data that can be stored in a column of a database table. They specify the range of values that a column can hold and the operations that can be performed on it. Each data type has specific properties, such as size, precision, and format, which determine how data is stored and manipulated within the database. Choosing the appropriate data type is crucial for efficient storage and retrieval of data.
INTEGER: Used for storing whole numbers.
CREATE TABLE employees ( employee_id INTEGER,
name VARCHAR(50),
age INTEGER );
VARCHAR(n):
Variable-length character string with a maximum length of 'n'.
CREATE TABLE products ( product_id INTEGER, name VARCHAR(100),
description VARCHAR(255) );
DECIMAL(p, s):
Fixed-point number with 'p' digits in total, with 's' digits after the decimal
point.
CREATE TABLE invoices ( invoice_number INTEGER, amount
DECIMAL(10, 2) );
DATE: Used for storing dates.
CREATE TABLE orders ( order_id INTEGER, order_date DATE
);
BOOLEAN: Used for storing boolean values
(true/false).
CREATE TABLE customers ( customer_id INTEGER, active BOOLEAN
);
BLOB: Binary Large Object, used for storing large
binary data such as images or documents.
CREATE TABLE documents ( document_id INTEGER, content BLOB
);
ENUM: A string object with a value chosen from a
predefined list of values.
CREATE TABLE survey ( survey_id INTEGER, response
ENUM('Strongly Agree', 'Agree', 'Neutral', 'Disagree', 'Strongly Disagree') );
TIMESTAMP: Used for storing date and time values.
CREATE TABLE logs ( log_id INTEGER, log_time TIMESTAMP
);
These are just a few examples of SQL data types. The specific data types available can vary depending on the SQL database system being used (e.g., MySQL, PostgreSQL, SQLite, etc.
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