chore: 恢复旧布局基线（迁移改动丢失后重建，apps/packages 布局暂存）

server/internal/db/ddl.go

@@ -0,0 +1,121 @@
+package db
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"strings"
+)
+
+// GetDDL 返回表/视图的建表语句。mysql 族走 SHOW CREATE TABLE,sqlite 读 sqlite_master,
+// pg/mssql/oracle 用 ListColumns 元数据在 Go 侧拼装 CREATE TABLE。
+func GetDDL(ctx context.Context, c ConnReq) (string, error) {
+	ctx = reqCtx(ctx)
+	if c.Table == "" {
+		return "", fmt.Errorf("缺少表名")
+	}
+	if isRedis(c.Driver) {
+		return "", fmt.Errorf("该驱动不支持 DDL 查看")
+	}
+	// pg/mssql/oracle:复用列元数据拼装,避免再查一次库
+	switch {
+	case isPostgresFamily(c.Driver), isMSSQL(c.Driver), driverKey(c.Driver) == "oracle":
+		cols, err := ListColumns(ctx, c)
+		if err != nil {
+			return "", err
+		}
+		return buildDDLFromColumns(c.Driver, c.Table, cols)
+	}
+	var out string
+	err := withDB(c, func(db *sql.DB) error {
+		var err error
+		switch {
+		case isMySQLFamily(c.Driver):
+			out, err = getDDLMySQL(ctx, db, c)
+		case driverKey(c.Driver) == "sqlite":
+			out, err = getDDLSQLite(ctx, db, c.Table)
+		default:
+			err = unsupportedDriverErr(c)
+		}
+		return err
+	})
+	if err != nil {
+		return "", err
+	}
+	return out, nil
+}
+
+// getDDLMySQL SHOW CREATE TABLE 第二列即 DDL(列名随对象类型变化:Create Table/Create View)。
+func getDDLMySQL(ctx context.Context, dbh *sql.DB, c ConnReq) (string, error) {
+	ident := quoteMySQLIdent(c.Table)
+	if c.Database != "" {
+		ident = quoteMySQLIdent(c.Database) + "." + ident
+	}
+	rows, err := dbh.QueryContext(ctx, "SHOW CREATE TABLE "+ident)
+	if err != nil {
+		return "", err
+	}
+	defer rows.Close()
+	if rows.Next() {
+		var name string
+		var ddl sql.NullString
+		if err := rows.Scan(&name, &ddl); err != nil {
+			return "", err
+		}
+		if !ddl.Valid {
+			return "", fmt.Errorf("无法读取 %s 的 DDL", c.Table)
+		}
+		return ddl.String, nil
+	}
+	if err := rows.Err(); err != nil {
+		return "", err
+	}
+	return "", fmt.Errorf("表 %s 不存在", c.Table)
+}
+
+// getDDLSQLite sqlite_master 的 sql 列即建表语句。
+func getDDLSQLite(ctx context.Context, dbh *sql.DB, table string) (string, error) {
+	var ddl sql.NullString
+	err := dbh.QueryRowContext(ctx, `SELECT sql FROM sqlite_master WHERE name = ?`, table).Scan(&ddl)
+	if err == sql.ErrNoRows {
+		return "", fmt.Errorf("表 %s 不存在", table)
+	}
+	if err != nil {
+		return "", err
+	}
+	if !ddl.Valid {
+		return "", fmt.Errorf("表 %s 无 DDL 记录", table)
+	}
+	return ddl.String, nil
+}
+
+// buildDDLFromColumns 用列元数据拼装 CREATE TABLE(类型直接用 ColumnInfo.Type)。
+func buildDDLFromColumns(driver, table string, cols []ColumnInfo) (string, error) {
+	if len(cols) == 0 {
+		return "", fmt.Errorf("表 %s 不存在或无列", table)
+	}
+	var pks []string
+	for _, col := range cols {
+		if col.Key == "PRI" {
+			pks = append(pks, quoteIdentFor(driver, col.Name))
+		}
+	}
+	var b strings.Builder
+	fmt.Fprintf(&b, "CREATE TABLE %s (\n", quoteTableNameFor(driver, table))
+	for i, col := range cols {
+		line := "  " + quoteIdentFor(driver, col.Name) + " " + col.Type
+		if !col.Nullable {
+			line += " NOT NULL"
+		}
+		// 非最后一列、或后面还有 PRIMARY KEY 子句时需要逗号
+		if i < len(cols)-1 || len(pks) > 0 {
+			line += ","
+		}
+		b.WriteString(line + "\n")
+	}
+	if len(pks) > 0 {
+		b.WriteString("  PRIMARY KEY (" + strings.Join(pks, ", ") + ")\n")
+	}
+	b.WriteString(");\n")
+	return b.String(), nil
+}