Detailed Explanation of MySQL Data Types: Basic Type Selection for Beginners

Data types are fundamental in MySQL; choosing the wrong one can lead to issues like data overflow or wasted space, making it crucial for writing effective SQL. This article explains from three aspects: importance, type classification, and selection principles. **Numeric Types**: Integers (TINYINT/SMALLINT/INT/BIGINT, with increasing ranges; use UNSIGNED to avoid negative value waste); Floats (FLOAT/DOUBLE, low precision, suitable for non-financial scenarios); Fixed-point numbers (DECIMAL, high precision, for exact calculations like amounts). **String Types**: Fixed-length CHAR(M) (suitable for short fixed text but space-wasting); Variable-length VARCHAR(M) (space-efficient but requires extra length storage); TEXT (stores ultra-long text, no default values allowed). **Date and Time**: DATE (date only); DATETIME (full date and time); TIMESTAMP (4 bytes, short range but auto-updates, suitable for time-sensitive data). **Other Types**: TINYINT(1) as a boolean alternative; ENUM (single selection from predefined values); SET (multiple selections from predefined values). **Selection Principles**: Prioritize the smallest appropriate type; choose based on requirements (e.g., VARCHAR for phone numbers, DECIMAL for amounts); avoid overusing NULL; strictly prohibit incorrect use of INT for phone numbers, etc.