MySQL WHERE Clause: A Beginner's Guide to Mastering Basic Data Filtering Methods

This article introduces the usage of the WHERE clause in MySQL, which is part of the SELECT statement used to filter records that meet specific conditions. The core content includes: 1. **Basic Conditions**: Equality (=) and inequality (!= or <>) apply to numeric values and strings (strings must be enclosed in single quotes). 2. **Range Conditions**: >, <, >=, <=, or the more concise BETWEEN...AND... (includes both endpoints). 3. **Logical Combinations**: AND (all conditions met), OR (any condition met), NOT (negation). Note that AND has higher precedence than OR; parentheses can be used for complex logic. 4. **Fuzzy Query**: LIKE combined with % (any characters) or _ (single character), e.g., %张% matches names containing "Zhang". 5. **Null Value Handling**: Use IS NULL / IS NOT NULL to check for null values; = or != cannot be used. Notes: Strings must be enclosed in single quotes, BETWEEN includes endpoints, and avoid direct null judgment with = or !=. The WHERE clause is the core of data filtering; mastering condition types and special handling allows flexible extraction of target data.