119 lines
4.5 KiB
Go
119 lines
4.5 KiB
Go
package cli
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import (
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"context"
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"database/sql"
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"fmt"
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"io"
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"strings"
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)
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func dumpMySQLTriggers(ctx context.Context, tx *sql.Tx, output io.Writer) error {
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// 名称排序不能代表执行顺序；同一表、时机和事件按服务器的 ACTION_ORDER 导出。
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rows, err := tx.QueryContext(ctx, `SELECT TRIGGER_NAME FROM information_schema.TRIGGERS
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WHERE TRIGGER_SCHEMA = DATABASE()
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ORDER BY EVENT_OBJECT_TABLE, ACTION_TIMING, EVENT_MANIPULATION, ACTION_ORDER`)
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if err != nil {
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return fmt.Errorf("读取 MySQL 触发器列表失败：%w", err)
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}
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var names []string
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for rows.Next() {
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var name string
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if err := rows.Scan(&name); err != nil {
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_ = rows.Close()
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return fmt.Errorf("读取 MySQL 触发器名称失败：%w", err)
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}
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names = append(names, name)
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}
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if err := rows.Err(); err != nil {
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_ = rows.Close()
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return fmt.Errorf("遍历 MySQL 触发器失败：%w", err)
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}
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if err := rows.Close(); err != nil {
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return err
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}
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if len(names) == 0 {
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return nil
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}
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var databaseCollation string
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if err := tx.QueryRowContext(ctx, "SELECT @@collation_database").Scan(&databaseCollation); err != nil {
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return fmt.Errorf("读取 MySQL 数据库排序规则失败：%w", err)
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}
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if _, err := fmt.Fprintln(output, `SET @scert_trigger_sql_mode = @@SESSION.sql_mode;
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SET @scert_trigger_charset = @@SESSION.character_set_client;
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SET @scert_trigger_collation = @@SESSION.collation_connection;`); err != nil {
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return err
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}
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for _, name := range names {
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definition, err := readMySQLTrigger(ctx, tx, name)
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if err != nil {
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return err
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}
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// 文件中的创建语句使用原客户端字符集，恢复时才能同时保留正文和创建元数据。
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var encoded, roundTrip []byte
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charset := quoteMySQLIdentifier(definition["character_set_client"])
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query := "SELECT CAST(CONVERT(? USING " + charset + ") AS BINARY), CAST(CONVERT(CONVERT(? USING " + charset + ") USING utf8mb4) AS BINARY)"
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original := definition["SQL Original Statement"]
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if err := tx.QueryRowContext(ctx, query, original, original).Scan(&encoded, &roundTrip); err != nil {
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return fmt.Errorf("转换 MySQL 触发器字符集失败（%s）：%w", name, err)
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}
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if string(roundTrip) != original {
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return fmt.Errorf("MySQL 触发器无法无损转换到创建字符集（%s）", name)
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}
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delimiter := ";;"
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for strings.Contains(string(encoded), delimiter) {
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delimiter += ";"
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}
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_, err = fmt.Fprintf(output, "ALTER DATABASE COLLATE %s;\nSET SESSION sql_mode = %s;\nSET SESSION character_set_client = %s;\nSET SESSION collation_connection = %s;\nDELIMITER %s\n%s%s\nDELIMITER ;\n",
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quoteMySQLIdentifier(definition["Database Collation"]), mysqlStringLiteral(definition["sql_mode"]),
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mysqlStringLiteral(definition["character_set_client"]), mysqlStringLiteral(definition["collation_connection"]), delimiter, encoded, delimiter)
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if err != nil {
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return fmt.Errorf("写入 MySQL 触发器失败（%s）：%w", name, err)
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}
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}
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_, err = fmt.Fprintf(output, "ALTER DATABASE COLLATE %s;\nSET SESSION sql_mode = @scert_trigger_sql_mode;\nSET SESSION character_set_client = @scert_trigger_charset;\nSET SESSION collation_connection = @scert_trigger_collation;\n\n", quoteMySQLIdentifier(databaseCollation))
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return err
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}
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func readMySQLTrigger(ctx context.Context, tx *sql.Tx, name string) (map[string]string, error) {
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rows, err := tx.QueryContext(ctx, "SHOW CREATE TRIGGER "+quoteMySQLIdentifier(name))
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if err != nil {
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return nil, fmt.Errorf("读取 MySQL 触发器定义失败（%s）：%w", name, err)
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}
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defer rows.Close()
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columns, err := rows.Columns()
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if err != nil {
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return nil, err
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}
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values := make([]sql.NullString, len(columns))
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pointers := make([]any, len(columns))
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for i := range values {
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pointers[i] = &values[i]
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}
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if !rows.Next() {
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if err := rows.Err(); err != nil {
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return nil, err
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}
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return nil, fmt.Errorf("MySQL 触发器定义不可见（%s）", name)
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}
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if err := rows.Scan(pointers...); err != nil {
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return nil, err
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}
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definition := make(map[string]string, len(columns))
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for i, column := range columns {
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if values[i].Valid {
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definition[column] = values[i].String
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}
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}
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for _, column := range []string{"sql_mode", "SQL Original Statement", "character_set_client", "collation_connection", "Database Collation"} {
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value, exists := definition[column]
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if !exists || (value == "" && column != "sql_mode") {
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return nil, fmt.Errorf("MySQL 触发器定义字段不完整（%s）：%s", name, column)
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}
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}
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if rows.Next() {
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return nil, fmt.Errorf("MySQL 触发器定义返回了多行（%s）", name)
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}
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return definition, rows.Err()
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}
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