fix(sql_helpers): strip empty RHS conditions from SQL strings

* Add regex patterns to identify and remove empty comparisons
* Implement tests for stripping empty RHS conditions
fix(handler): prevent duplicate JOIN aliases from preload
* Skip custom SQL JOINs if alias already provided by preload
* Split multiple JOIN clauses for individual alias handling

pkg/common/adapters/database/bun.go

@@ -487,6 +487,14 @@ func normalizeTableAlias(query, expectedAlias, tableName string) string {
 	return modified
 }
 
+func isJoinKeyword(word string) bool {
+	switch strings.ToUpper(word) {
+	case "JOIN", "INNER", "LEFT", "RIGHT", "FULL", "OUTER", "CROSS":
+		return true
+	}
+	return false
+}
+
 func (b *BunSelectQuery) WhereOr(query string, args ...interface{}) common.SelectQuery {
 	b.query = b.query.WhereOr(query, args...)
 	return b
@@ -517,7 +525,7 @@ func (b *BunSelectQuery) Join(query string, args ...interface{}) common.SelectQu
 	if prefix != "" && !strings.Contains(strings.ToUpper(query), " AS ") {
 		// If query doesn't already have AS, check if it's a simple table name
 		parts := strings.Fields(query)
-		if len(parts) > 0 && !strings.HasPrefix(strings.ToUpper(parts[0]), "JOIN") {
+		if len(parts) > 0 && !isJoinKeyword(parts[0]) {
 			// Simple table name, add prefix: "table AS prefix"
 			joinClause = fmt.Sprintf("%s AS %s", parts[0], prefix)
 			if len(parts) > 1 {
@@ -552,7 +560,7 @@ func (b *BunSelectQuery) LeftJoin(query string, args ...interface{}) common.Sele
 	joinClause := query
 	if prefix != "" && !strings.Contains(strings.ToUpper(query), " AS ") {
 		parts := strings.Fields(query)
-		if len(parts) > 0 && !strings.HasPrefix(strings.ToUpper(parts[0]), "LEFT") && !strings.HasPrefix(strings.ToUpper(parts[0]), "JOIN") {
+		if len(parts) > 0 && !isJoinKeyword(parts[0]) {
 			joinClause = fmt.Sprintf("%s AS %s", parts[0], prefix)
 			if len(parts) > 1 {
 				joinClause += " " + strings.Join(parts[1:], " ")

pkg/common/sql_helpers.go

@@ -59,6 +59,38 @@ func IsSQLExpression(cond string) bool {
 	return false
 }
 
+// reEmptyCompMid matches a simple column comparison with an empty RHS that is immediately
+// followed by AND/OR (only whitespace between the operator and the next keyword).
+// Removing the match leaves the preceding AND/OR connector intact.
+// Example: "cond1 and col = \n    and cond2" → "cond1 and cond2"
+var reEmptyCompMid = regexp.MustCompile(`(?i)[\w.]+\s*(?:=|<>|!=|>=|<=|>|<)\s+(?:and|or)\s+`)
+
+// reEmptyCompEnd matches AND/OR + a simple column comparison with an empty RHS at the end
+// of the string (or sub-clause).
+// Example: "cond1 and col = " → "cond1"
+var reEmptyCompEnd = regexp.MustCompile(`(?i)\s+(?:and|or)\s+[\w.]+\s*(?:=|<>|!=|>=|<=|>|<)\s*$`)
+
+// stripEmptyComparisonClauses removes comparison conditions that have no right-hand side
+// value from a raw SQL string. Operates on the whole string so it also cleans up conditions
+// inside subqueries, not just top-level AND splits.
+func stripEmptyComparisonClauses(sql string) string {
+	sql = reEmptyCompMid.ReplaceAllLiteralString(sql, "")
+	sql = reEmptyCompEnd.ReplaceAllLiteralString(sql, "")
+	return sql
+}
+
+// hasEmptyRHS returns true when a condition ends with a comparison operator and has no
+// right-hand side value — e.g., "col = ", "com.rid_parent = ", "col >= ".
+func hasEmptyRHS(cond string) bool {
+	cond = strings.TrimSpace(cond)
+	for _, op := range []string{"<>", "!=", ">=", "<=", "=", ">", "<"} {
+		if strings.HasSuffix(cond, op) {
+			return true
+		}
+	}
+	return false
+}
+
 // IsTrivialCondition checks if a condition is trivial and always evaluates to true
 // These conditions should be removed from WHERE clauses as they have no filtering effect
 func IsTrivialCondition(cond string) bool {
@@ -147,6 +179,14 @@ func SanitizeWhereClause(where string, tableName string, options ...*RequestOpti
 		return ""
 	}
 
+	// Strip comparison conditions with empty RHS throughout the SQL string (including
+	// inside subqueries), before condition splitting.
+	where = stripEmptyComparisonClauses(where)
+	if where == "" {
+		return ""
+	}
+	where = strings.TrimSpace(where)
+
 	// Check if the original clause has outer parentheses and contains OR operators
 	// If so, we need to preserve the outer parentheses to prevent OR logic from escaping
 	hasOuterParens := false
@@ -212,6 +252,12 @@ func SanitizeWhereClause(where string, tableName string, options ...*RequestOpti
 			continue
 		}
 
+		// Skip conditions with no right-hand side value (e.g. "col = " with empty value)
+		if hasEmptyRHS(condToCheck) {
+			logger.Debug("Removing condition with empty value: '%s'", cond)
+			continue
+		}
+
 		// If tableName is provided and the condition HAS a table prefix, check if it's correct
 		if tableName != "" && hasTablePrefix(condToCheck) {
 			// Extract the current prefix and column name

pkg/common/sql_helpers_test.go

@@ -134,6 +134,30 @@ func TestSanitizeWhereClause(t *testing.T) {
 			tableName: "apiprovider",
 			expected:  "apiprovider.type in ('softphone') AND (apiprovider.rid_apiprovider in (select l.rid_apiprovider from core.apiproviderlink l where l.rid_hub = 2576))",
 		},
+		{
+			name:      "empty RHS stripped mid-clause",
+			where:     "com.tableprefix = 'tcli' and com.rid_parent = \n    and com.status = 'Active'",
+			tableName: "",
+			expected:  "com.tableprefix = 'tcli' AND com.status = 'Active'",
+		},
+		{
+			name:      "empty RHS stripped at end of clause",
+			where:     "com.tableprefix = 'tcli' and com.rid_parent =",
+			tableName: "",
+			expected:  "com.tableprefix = 'tcli'",
+		},
+		{
+			name:      "non-empty value not stripped",
+			where:     "com.tableprefix = 'tcli' and com.rid_parent = 123 and com.status = 'Active'",
+			tableName: "",
+			expected:  "com.tableprefix = 'tcli' AND com.rid_parent = 123 AND com.status = 'Active'",
+		},
+		{
+			name:      "empty RHS inside subquery stripped",
+			where:     "a = 1 and b in (select x from t where c.rid = \n    and d = 2)",
+			tableName: "",
+			expected:  "a = 1 AND b in (select x from t where d = 2)",
+		},
 	}
 
 	for _, tt := range tests {