MySQL Data Backup and Recovery: A Basic Data Security Guide for Beginners
Data backup and recovery are core aspects of MySQL operations and maintenance, preventing data loss. The key tool is `mysqldump`, which can back up an entire database, a single table (e.g., the `users` table), or filter data by conditions (e.g., `age>18`). For advanced needs, `xtrabackup` supports hot backups without service downtime. Recovery is performed via the `mysql` command-line tool, allowing restoration to an existing database or a new instance. To avoid oversight, use `crontab` to set up regular backups (scripts should include compression and cleanup of old backups). Before recovery, verify backup integrity, clear the target database, and disable non-essential services (e.g., foreign key constraints). Common issues like insufficient permissions or non-existent tables can be resolved by checking account credentials and creating the target database. Key points: Proficient use of `mysqldump`, regular backups, monthly recovery testing, and ensuring data security.
Read MoreDetailed 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.
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