docs: Add CLAUDE.md with codebase guidance

Create comprehensive documentation for future Claude Code instances working in this repository, including:
- Development commands for testing, building, and code quality
- Core architecture overview of the SQL query builder system
- Directory structure and component explanations
- Testing patterns and conventions
- Key dependencies and their purposes

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

internal/util/column_map.go

@@ -5,7 +5,7 @@ import (
 	"sort"
 	"strings"
 
-	"git.fsdpf.net/go/db/v2/internal/tag"
+	"git.fsdpf.net/go/db/internal/tag"
 )
 
 type (
@@ -37,13 +37,14 @@ func newColumnMap(t reflect.Type, fieldIndex []int, prefixes []string) ColumnMap
 			// if PkgPath is empty then it is an exported field
 			columnName := getColumnName(&f, dbTag)
 			if !shouldIgnoreField(dbTag) {
-				if !implementsScanner(f.Type) {
-					subCm := getStructColumnMap(&f, fieldIndex, []string{columnName}, prefixes)
-					if len(subCm) != 0 {
-						subColMaps = append(subColMaps, subCm)
-						continue
-					}
-				}
+				// 移除原来的关联结构,并 scans 字段出现 table.col
+				// if !implementsScanner(f.Type) {
+				// 	subCm := getStructColumnMap(&f, fieldIndex, []string{columnName}, prefixes)
+				// 	if len(subCm) != 0 {
+				// 		subColMaps = append(subColMaps, subCm)
+				// 		continue
+				// 	}
+				// }
 				ffTag := tag.New("ff", f.Tag)
 				columnName = strings.Join(append(prefixes, columnName), ".")
 				cm[columnName] = newColumnData(&f, columnName, fieldIndex, ffTag)