From cc0e6b8c1289d59d3b18d0f85eb0e726723562cf Mon Sep 17 00:00:00 2001
From: ls0 <ls0@oceanbase.com>
Date: Wed, 25 Aug 2021 11:09:16 +0800
Subject: [PATCH] implement sql_mode NO_UNSIGNED_SUBTRACTION

---
 deps/oblib/src/common/object/ob_obj_type.h    | 32 +++++++++++++++++++
 .../src/common/sql_mode/ob_sql_mode_utils.cpp |  2 +-
 .../src/common/sql_mode/ob_sql_mode_utils.h   |  6 ++++
 src/sql/engine/expr/ob_expr_minus.cpp         | 11 ++++++-
 4 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/deps/oblib/src/common/object/ob_obj_type.h b/deps/oblib/src/common/object/ob_obj_type.h
index 77410e1484..a9a2e2bc75 100644
--- a/deps/oblib/src/common/object/ob_obj_type.h
+++ b/deps/oblib/src/common/object/ob_obj_type.h
@@ -1228,6 +1228,38 @@ inline bool ob_is_unsigned_type(ObObjType type)
          ObUDoubleType == type || ObUNumberType == type;
 }
 
+inline void convert_unsigned_type_to_signed(ObObjType &type)
+{
+  switch (type) {
+    case (ObUTinyIntType):
+      type = ObTinyIntType;
+      break;
+    case (ObUSmallIntType):
+      type = ObSmallIntType;
+      break;
+    case (ObUMediumIntType):
+      type = ObMediumIntType;
+      break;
+    case (ObUInt32Type):
+      type = ObInt32Type;
+      break;
+    case (ObUInt64Type):
+      type = ObIntType;
+      break;
+    case (ObUFloatType):
+      type = ObFloatType;
+      break;
+    case (ObUDoubleType):
+      type = ObDoubleType;
+      break;
+    case (ObUNumberType):
+      type = ObNumberType;
+      break;
+    default:
+      break;
+  }
+}
+
 inline bool ob_is_oracle_numeric_type(ObObjType type)
 {
   return ObIntType == type || ob_is_number_tc(type) || ObFloatType == type || ObDoubleType == type;
diff --git a/deps/oblib/src/common/sql_mode/ob_sql_mode_utils.cpp b/deps/oblib/src/common/sql_mode/ob_sql_mode_utils.cpp
index 78cca32524..181f6a7651 100644
--- a/deps/oblib/src/common/sql_mode/ob_sql_mode_utils.cpp
+++ b/deps/oblib/src/common/sql_mode/ob_sql_mode_utils.cpp
@@ -60,7 +60,7 @@ ObSqlModeMap SQL_MODE_MAP[] = {{SMO_REAL_AS_FLOAT, STR_REAL_AS_FLOAT},
 
 ObSQLMode SUPPORT_MODE = SMO_STRICT_ALL_TABLES | SMO_STRICT_TRANS_TABLES | SMO_PAD_CHAR_TO_FULL_LENGTH |
                          SMO_ONLY_FULL_GROUP_BY | SMO_NO_AUTO_VALUE_ON_ZERO | SMO_PIPES_AS_CONCAT |
-                         SMO_HIGH_NOT_PRECEDENCE | SMO_ERROR_ON_RESOLVE_CAST;
+                         SMO_HIGH_NOT_PRECEDENCE | SMO_ERROR_ON_RESOLVE_CAST | SMO_NO_UNSIGNED_SUBTRACTION;
 
 bool is_sql_mode_supported(ObSQLMode mode)
 {
diff --git a/deps/oblib/src/common/sql_mode/ob_sql_mode_utils.h b/deps/oblib/src/common/sql_mode/ob_sql_mode_utils.h
index e2d25fcd52..a26fba0a36 100644
--- a/deps/oblib/src/common/sql_mode/ob_sql_mode_utils.h
+++ b/deps/oblib/src/common/sql_mode/ob_sql_mode_utils.h
@@ -45,6 +45,12 @@ inline bool is_no_zero_date(ObSQLMode mode)
 {
   return (SMO_NO_ZERO_DATE & mode);
 }
+
+inline bool is_no_unsigned_subtraction(ObSQLMode mode)
+{
+  return (SMO_NO_UNSIGNED_SUBTRACTION & mode);
+}
+
 inline bool is_mysql_compatible(ObCompatibilityMode mode)
 {
   return OCEANBASE_MODE == mode || MYSQL_MODE == mode;
diff --git a/src/sql/engine/expr/ob_expr_minus.cpp b/src/sql/engine/expr/ob_expr_minus.cpp
index a4e5bcabf7..13be668af1 100644
--- a/src/sql/engine/expr/ob_expr_minus.cpp
+++ b/src/sql/engine/expr/ob_expr_minus.cpp
@@ -42,8 +42,12 @@ int ObExprMinus::calc_result_type2(
   static const int64_t CARRY_OFFSET = 1;
   ObScale scale = SCALE_UNKNOWN_YET;
   ObPrecision precision = PRECISION_UNKNOWN_YET;
+  const ObSQLSessionInfo *session = nullptr;
   bool is_oracle = share::is_oracle_mode();
-  if (OB_FAIL(ObArithExprOperator::calc_result_type2(type, type1, type2, type_ctx))) {
+  if (OB_ISNULL(session = type_ctx.get_session())) {
+    ret = OB_ERR_UNEXPECTED;
+    LOG_WARN("failed to get mysession", K(ret));
+  } else if (OB_FAIL(ObArithExprOperator::calc_result_type2(type, type1, type2, type_ctx))) {
     LOG_WARN("fail to calc result type", K(ret), K(type), K(type1), K(type2));
   } else if (is_oracle && type.is_oracle_decimal()) {
     type.set_scale(ORA_NUMBER_SCALE_UNKNOWN_YET);
@@ -78,6 +82,11 @@ int ObExprMinus::calc_result_type2(
     } else {
       type.set_precision(precision);
     }
+    if (share::is_mysql_mode() && is_no_unsigned_subtraction(session->get_sql_mode())) {
+      ObObjType convert_type = type.get_type();
+      convert_unsigned_type_to_signed(convert_type);
+      type.set_type(convert_type);
+    }
     LOG_DEBUG("calc_result_type2", K(scale), K(type1), K(type2), K(type), K(precision));
   }
   return ret;