Fix QuoteTo

Author: jinzhu

sqlite.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"database/sql"
 	"strconv"
-	"strings"
 
 	"gorm.io/gorm/callbacks"
 
@@ -143,19 +142,51 @@ func (dialector Dialector) BindVarTo(writer clause.Writer, stmt *gorm.Statement,
 }
 
 func (dialector Dialector) QuoteTo(writer clause.Writer, str string) {
-	writer.WriteByte('`')
-	if strings.Contains(str, ".") {
-		for idx, str := range strings.Split(str, ".") {
-			if idx > 0 {
-				writer.WriteString(".`")
+	var (
+		underQuoted, selfQuoted bool
+		continuousBacktick      int8
+		shiftDelimiter          int8
+	)
+
+	for _, v := range []byte(str) {
+		switch v {
+		case '`':
+			continuousBacktick++
+			if continuousBacktick == 2 {
+				writer.WriteString("``")
+				continuousBacktick = 0
+			}
+		case '.':
+			if continuousBacktick > 0 || !selfQuoted {
+				shiftDelimiter = 0
+				underQuoted = false
+				continuousBacktick = 0
+				writer.WriteString("`")
+			}
+			writer.WriteByte(v)
+			continue
+		default:
+			if shiftDelimiter-continuousBacktick <= 0 && !underQuoted {
+				writer.WriteString("`")
+				underQuoted = true
+				if selfQuoted = continuousBacktick > 0; selfQuoted {
+					continuousBacktick -= 1
+				}
+			}
+
+			for ; continuousBacktick > 0; continuousBacktick -= 1 {
+				writer.WriteString("``")
 			}
-			writer.WriteString(str)
-			writer.WriteByte('`')
+
+			writer.WriteByte(v)
 		}
-	} else {
-		writer.WriteString(str)
-		writer.WriteByte('`')
+		shiftDelimiter++
+	}
+
+	if continuousBacktick > 0 && !selfQuoted {
+		writer.WriteString("``")
 	}
+	writer.WriteString("`")
 }
 
 func (dialector Dialector) Explain(sql string, vars ...interface{}) string {