Support expr pi in mysql mode

src/sql/engine/expr/ob_expr_pi.cpp

@@ -0,0 +1,68 @@
+// Copyright 1999-2021 Alibaba Inc. All Rights Reserved.
+// Author:
+//   xiaofeng.lby@alipay.com
+//  Normalizer:
+//
+// This file is for implementation of func pi
+
+#define USING_LOG_PREFIX SQL_ENG
+#include "sql/engine/expr/ob_expr_pi.h"
+#include "sql/session/ob_sql_session_info.h"
+
+using namespace oceanbase::common;
+using namespace oceanbase::sql;
+
+namespace oceanbase
+{
+namespace sql
+{
+
+const double ObExprPi::mysql_pi_ = 3.14159265358979323846264338327950288;
+
+ObExprPi::ObExprPi(ObIAllocator &alloc)
+    : ObFuncExprOperator(alloc, T_FUN_SYS_PI, N_PI, 0, NOT_ROW_DIMENSION)
+{
+}
+
+ObExprPi::~ObExprPi()
+{
+}
+
+int ObExprPi::calc_result_type0(ObExprResType &type, ObExprTypeCtx &type_ctx) const
+{
+  UNUSED(type_ctx);
+  type.set_double();
+  type.set_precision(-1);
+  type.set_scale(6);
+  return OB_SUCCESS;
+}
+
+int ObExprPi::calc_result0(ObObj &result, ObExprCtx &expr_ctx) const
+{
+  UNUSED(expr_ctx);
+  int ret = OB_SUCCESS;
+  result.set_double(mysql_pi_);
+  return ret;
+}
+
+int ObExprPi::eval_pi(const ObExpr &expr, ObEvalCtx &ctx,
+    ObDatum &expr_datum)
+{
+  UNUSED(expr);
+  UNUSED(ctx);
+  int ret = OB_SUCCESS;
+  expr_datum.set_double(mysql_pi_);
+  return ret;
+}
+
+int ObExprPi::cg_expr(ObExprCGCtx &op_cg_ctx, const ObRawExpr &raw_expr,
+    ObExpr &rt_expr) const
+{
+  UNUSED(op_cg_ctx);
+  UNUSED(raw_expr);
+  rt_expr.eval_func_ = ObExprPi::eval_pi;
+  return OB_SUCCESS;
+}
+
+} //namespace sql
+} //namespace oceanbase