Fix quote/unquote logic for default values

Author: AlexanderShelyugov

element/column.go

@@ -208,15 +208,19 @@ func (c Column) pkDefinition(isPrev bool) (string, bool) {
 		if sql.IsSqlite() {
 			// SQLite overrides, that pingcap doesn't support
 			if opt.Tp == ast.ColumnOptionDefaultValue {
+				// Parsed StrValue may be quoted in single quotes, which breaks SQL expression.
+				// We need to unquote it and, if it's a TEXT column. quote it again with double quotes.
 				expression, err := strconv.Unquote(opt.StrValue)
 				if err != nil {
 					expression = opt.StrValue
 				}
 				if len(expression) >= 2 && expression[0] == '\'' && expression[len(expression)-1] == '\'' {
 					// remove single quotes. strconv may not detect it
-					expression = strconv.Quote(expression[1 : len(expression)-1])
+					expression = expression[1 : len(expression)-1]
+				}
+				if c.typeDefinition(isPrev) == "TEXT" {
+					expression = strconv.Quote(expression)
 				}
-
 				strSql += " DEFAULT " + expression
 				continue
 			}