CREATE Table

The CREATE TABLE statement is used to define a new table in a database - specifying its name, columns, and the data type and constraints for each column.

Basic Syntax

CREATE TABLE customers (
    customer_id INT PRIMARY KEY,
    first_name  VARCHAR(50) NOT NULL,
    email       VARCHAR(100) UNIQUE,
    city        VARCHAR(50),
    signup_date DATE
);

Common Data Types

  • INT - whole numbers
  • VARCHAR(n) - variable-length text up to n characters
  • DATE / DATETIME - date and time values
  • DECIMAL(p, s) - precise decimal numbers, useful for currency
  • BOOLEAN - true/false values

Common Constraints

  • PRIMARY KEY - uniquely identifies each row
  • NOT NULL - column cannot be left empty
  • UNIQUE - all values in the column must be different
  • FOREIGN KEY - links a column to another table's primary key
Choosing the right data type and constraints upfront in CREATE TABLE prevents a lot of data-quality problems later - it's much harder to fix bad data than to prevent it.

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