add method SelectCount ....

crud.go

@@ -25,6 +25,8 @@ const NotLike = "NOT LIKE"
 const Between = "BETWEEN"
 const NotBetween = "NOT BETWEEN"
 
+const Raw = "Raw"
+
 type WhereItem struct {
 	Field string
 	Opt   string
@@ -217,7 +219,7 @@ func (db *Executor) GetOne(obj interface{}) error {
 
 func (db *Executor) getSqlAndParams() (string, []any) {
 	var paramList []any
-	fieldStr := handleField(db.SelectList)
+	fieldStr, paramList := handleField(db.SelectList, db.SelectExpList, paramList)
 	whereStr, paramList := handleWhere(db.WhereList, paramList)
 	joinStr := handleJoin(db.JoinList)
 	groupStr := handleGroup(db.GroupList)
@@ -548,6 +550,45 @@ func (db *Executor) Select(f string) *Executor {
 	return db
 }
 
+// SelectCount 链式操作-count(field) as field_new
+func (db *Executor) SelectCount(f string, fieldNew string) *Executor {
+	db.SelectList = append(db.SelectList, "count("+f+") AS "+fieldNew)
+	return db
+}
+
+// SelectSum 链式操作-sum(field) as field_new
+func (db *Executor) SelectSum(f string, fieldNew string) *Executor {
+	db.SelectList = append(db.SelectList, "sum("+f+") AS "+fieldNew)
+	return db
+}
+
+// SelectMin 链式操作-min(field) as field_new
+func (db *Executor) SelectMin(f string, fieldNew string) *Executor {
+	db.SelectList = append(db.SelectList, "min("+f+") AS "+fieldNew)
+	return db
+}
+
+// SelectMax 链式操作-max(field) as field_new
+func (db *Executor) SelectMax(f string, fieldNew string) *Executor {
+	db.SelectList = append(db.SelectList, "max("+f+") AS "+fieldNew)
+	return db
+}
+
+// SelectAvg 链式操作-avg(field) as field_new
+func (db *Executor) SelectAvg(f string, fieldNew string) *Executor {
+	db.SelectList = append(db.SelectList, "avg("+f+") AS "+fieldNew)
+	return db
+}
+
+// SelectExp 链式操作-表达式
+func (db *Executor) SelectExp(db2 *Executor, fieldNew string) *Executor {
+	db.SelectExpList = append(db.SelectExpList, ExpItem{
+		Executor:  db2,
+		FieldName: fieldNew,
+	})
+	return db
+}
+
 // Table 链式操作-从哪个表查询,允许直接写别名,例如 person p
 func (db *Executor) Table(tableName string) *Executor {
 	db.TableName = tableName
@@ -661,12 +702,19 @@ func (db *Executor) LockForUpdate(isLockForUpdate bool) *Executor {
 }
 
 //拼接SQL,字段相关
-func handleField(selectList []string) string {
-	if len(selectList) == 0 {
-		return "*"
+func handleField(selectList []string, selectExpList []ExpItem, paramList []any) (string, []any) {
+	if len(selectList) == 0 && len(selectExpList) == 0 {
+		return "*", paramList
 	}
 
-	return strings.Join(selectList, ",")
+	//处理子语句
+	for i := 0; i < len(selectExpList); i++ {
+		subSql, subParamList := selectExpList[i].Executor.getSqlAndParams()
+		selectList = append(selectList, "("+subSql+") AS "+selectExpList[i].FieldName)
+		paramList = append(paramList, subParamList...)
+	}
+
+	return strings.Join(selectList, ","), paramList
 }
 
 //拼接SQL,查询条件
@@ -816,6 +864,10 @@ func whereAndHaving(where []WhereItem, paramList []any) ([]string, []any) {
 			whereList = append(whereList, where[i].Field+" "+where[i].Opt+" "+"("+strings.Join(placeholder, ",")+")")
 			paramList = append(paramList, values...)
 		}
+
+		//if where[i].Opt == Raw {
+		//	whereList = append(whereList, where[i].Field+" "+fmt.Sprintf("%v", where[i].Val))
+		//}
 	}
 
 	return whereList, paramList