From 89d0878913a1f752cbeb0e16ccc46b9d0694d476 Mon Sep 17 00:00:00 2001
From: rulego-team <rulego@outlook.com>
Date: Mon, 16 Jun 2025 20:25:27 +0800
Subject: [PATCH] =?UTF-8?q?feat:HAVING=E5=AD=90=E5=8F=A5=E4=B8=AD=E6=94=AF?=
 =?UTF-8?q?=E6=8C=81CASE=E8=A1=A8=E8=BE=BE=E5=BC=8F?=
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---
 stream/stream.go | 84 ++++++++++++++++++++++++++++++++++--------------
 1 file changed, 59 insertions(+), 25 deletions(-)

diff --git a/stream/stream.go b/stream/stream.go
index 72b6de3..0da0259 100644
--- a/stream/stream.go
+++ b/stream/stream.go
@@ -409,36 +409,70 @@ func (s *Stream) process() {
 
 					// 应用 HAVING 过滤条件
 					if s.config.Having != "" {
-						// 预处理HAVING条件中的LIKE语法，转换为expr-lang可理解的形式
-						processedHaving := s.config.Having
-						bridge := functions.GetExprBridge()
-						if bridge.ContainsLikeOperator(s.config.Having) {
-							if processed, err := bridge.PreprocessLikeExpression(s.config.Having); err == nil {
-								processedHaving = processed
-							}
-						}
+						// 检查HAVING条件是否包含CASE表达式
+						hasCaseExpression := strings.Contains(strings.ToUpper(s.config.Having), "CASE")
 
-						// 预处理HAVING条件中的IS NULL语法
-						if bridge.ContainsIsNullOperator(processedHaving) {
-							if processed, err := bridge.PreprocessIsNullExpression(processedHaving); err == nil {
-								processedHaving = processed
-							}
-						}
+						var filteredResults []map[string]interface{}
 
-						// 创建 HAVING 条件
-						havingFilter, err := condition.NewExprCondition(processedHaving)
-						if err != nil {
-							logger.Error("having filter error: %v", err)
-						} else {
-							// 应用 HAVING 过滤
-							var filteredResults []map[string]interface{}
-							for _, result := range finalResults {
-								if havingFilter.Evaluate(result) {
-									filteredResults = append(filteredResults, result)
+						if hasCaseExpression {
+							// HAVING条件包含CASE表达式，使用我们的表达式解析器
+							expression, err := expr.NewExpression(s.config.Having)
+							if err != nil {
+								logger.Error("having filter error (CASE expression): %v", err)
+							} else {
+								// 应用 HAVING 过滤，使用CASE表达式计算器
+								for _, result := range finalResults {
+									// 使用EvaluateWithNull方法以支持NULL值处理
+									havingResult, isNull, err := expression.EvaluateWithNull(result)
+									if err != nil {
+										logger.Error("having filter evaluation error: %v", err)
+										continue
+									}
+
+									// 如果结果是NULL，则不满足条件（SQL标准行为）
+									if isNull {
+										continue
+									}
+
+									// 对于数值结果，大于0视为true（满足HAVING条件）
+									if havingResult > 0 {
+										filteredResults = append(filteredResults, result)
+									}
+								}
+							}
+						} else {
+							// HAVING条件不包含CASE表达式，使用原有的expr-lang处理
+							// 预处理HAVING条件中的LIKE语法，转换为expr-lang可理解的形式
+							processedHaving := s.config.Having
+							bridge := functions.GetExprBridge()
+							if bridge.ContainsLikeOperator(s.config.Having) {
+								if processed, err := bridge.PreprocessLikeExpression(s.config.Having); err == nil {
+									processedHaving = processed
+								}
+							}
+
+							// 预处理HAVING条件中的IS NULL语法
+							if bridge.ContainsIsNullOperator(processedHaving) {
+								if processed, err := bridge.PreprocessIsNullExpression(processedHaving); err == nil {
+									processedHaving = processed
+								}
+							}
+
+							// 创建 HAVING 条件
+							havingFilter, err := condition.NewExprCondition(processedHaving)
+							if err != nil {
+								logger.Error("having filter error: %v", err)
+							} else {
+								// 应用 HAVING 过滤
+								for _, result := range finalResults {
+									if havingFilter.Evaluate(result) {
+										filteredResults = append(filteredResults, result)
+									}
 								}
 							}
-							finalResults = filteredResults
 						}
+
+						finalResults = filteredResults
 					}
 
 					// 应用 LIMIT 限制