diff --git a/pkg/funcspec/function_api.go b/pkg/funcspec/function_api.go
index 5577cae..b13ff56 100644
--- a/pkg/funcspec/function_api.go
+++ b/pkg/funcspec/function_api.go
@@ -522,10 +522,16 @@ func (h *Handler) SqlQuery(sqlquery string, options SqlQueryOptions) HTTPFuncTyp
 			if strings.HasPrefix(kLower, "x-fieldfilter-") {
 				colname := strings.ReplaceAll(kLower, "x-fieldfilter-", "")
 				if strings.Contains(strings.ToLower(sqlquery), colname) {
-					if val == "" || val == "0" {
-						sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("COALESCE(%s, 0) = %s", ValidSQL(colname, "colname"), ValidSQL(val, "colvalue")))
+					if val == "0" {
+						sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("COALESCE(%s, 0) = 0", ValidSQL(colname, "colname")))
+					} else if val == "" {
+						sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("(%[1]s = '' OR %[1]s IS NULL)", ValidSQL(colname, "colname")))
 					} else {
-						sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s = %s", ValidSQL(colname, "colname"), ValidSQL(val, "colvalue")))
+						if IsNumeric(val) {
+							sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s = %s", ValidSQL(colname, "colname"), ValidSQL(val, "colvalue")))
+						} else {
+							sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s = '%s'", ValidSQL(colname, "colname"), ValidSQL(val, "colvalue")))
+						}
 					}
 				}
 			}
@@ -662,7 +668,10 @@ func (h *Handler) mergePathParams(r *http.Request, sqlquery string, variables ma
 		for k, v := range pathVars {
 			kword := fmt.Sprintf("[%s]", k)
 			if strings.Contains(sqlquery, kword) {
-				sqlquery = strings.ReplaceAll(sqlquery, kword, fmt.Sprintf("%v", v))
+				// Sanitize the value before replacing
+				vStr := fmt.Sprintf("%v", v)
+				sanitized := ValidSQL(vStr, "colvalue")
+				sqlquery = strings.ReplaceAll(sqlquery, kword, sanitized)
 			}
 			variables[k] = v
 
@@ -690,7 +699,9 @@ func (h *Handler) mergeQueryParams(r *http.Request, sqlquery string, variables m
 		// Replace in SQL if placeholder exists
 		if strings.Contains(sqlquery, kword) && len(val) > 0 {
 			if strings.HasPrefix(parmk, "p-") {
-				sqlquery = strings.ReplaceAll(sqlquery, kword, val)
+				// Sanitize the parameter value before replacing
+				sanitized := ValidSQL(val, "colvalue")
+				sqlquery = strings.ReplaceAll(sqlquery, kword, sanitized)
 			}
 		}
 
@@ -702,15 +713,36 @@ func (h *Handler) mergeQueryParams(r *http.Request, sqlquery string, variables m
 		// Apply filters if allowed
 		if allowFilter && len(parmk) > 1 && strings.Contains(strings.ToLower(sqlquery), strings.ToLower(parmk)) {
 			if len(parmv) > 1 {
-				sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s IN (%s)", ValidSQL(parmk, "colname"), strings.Join(parmv, ",")))
+				// Sanitize each value in the IN clause with appropriate quoting
+				sanitizedValues := make([]string, len(parmv))
+				for i, v := range parmv {
+					if IsNumeric(v) {
+						// Numeric values don't need quotes
+						sanitizedValues[i] = ValidSQL(v, "colvalue")
+					} else {
+						// String values need quotes
+						sanitized := ValidSQL(v, "colvalue")
+						sanitizedValues[i] = fmt.Sprintf("'%s'", sanitized)
+					}
+				}
+				sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s IN (%s)", ValidSQL(parmk, "colname"), strings.Join(sanitizedValues, ",")))
 			} else {
 				if strings.Contains(val, "match=") {
 					colval := strings.ReplaceAll(val, "match=", "")
+					// Escape single quotes and backslashes for LIKE patterns
+					// But don't escape wildcards % and _ which are intentional
+					colval = strings.ReplaceAll(colval, "\\", "\\\\")
+					colval = strings.ReplaceAll(colval, "'", "''")
 					if colval != "*" {
-						sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s ILIKE '%%%s%%'", ValidSQL(parmk, "colname"), ValidSQL(colval, "colvalue")))
+						sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s ILIKE '%%%s%%'", ValidSQL(parmk, "colname"), colval))
 					}
 				} else if val == "" || val == "0" {
-					sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("(%[1]s = %[2]s OR %[1]s IS NULL)", ValidSQL(parmk, "colname"), ValidSQL(val, "colvalue")))
+					// For empty/zero values, treat as literal 0 or empty string with quotes
+					if val == "0" {
+						sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("(%[1]s = 0 OR %[1]s IS NULL)", ValidSQL(parmk, "colname")))
+					} else {
+						sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("(%[1]s = '' OR %[1]s IS NULL)", ValidSQL(parmk, "colname")))
+					}
 				} else {
 					if IsNumeric(val) {
 						sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s = %s", ValidSQL(parmk, "colname"), ValidSQL(val, "colvalue")))
@@ -743,16 +775,24 @@ func (h *Handler) mergeHeaderParams(r *http.Request, sqlquery string, variables
 
 		kword := fmt.Sprintf("[%s]", k)
 		if strings.Contains(sqlquery, kword) {
-			sqlquery = strings.ReplaceAll(sqlquery, kword, val)
+			// Sanitize the header value before replacing
+			sanitized := ValidSQL(val, "colvalue")
+			sqlquery = strings.ReplaceAll(sqlquery, kword, sanitized)
 		}
 
 		// Handle special headers
 		if strings.Contains(k, "x-fieldfilter-") {
 			colname := strings.ReplaceAll(k, "x-fieldfilter-", "")
-			if val == "" || val == "0" {
-				sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("COALESCE(%s, 0) = %s", ValidSQL(colname, "colname"), ValidSQL(val, "colvalue")))
+			if val == "0" {
+				sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("COALESCE(%s, 0) = 0", ValidSQL(colname, "colname")))
+			} else if val == "" {
+				sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("(%[1]s = '' OR %[1]s IS NULL)", ValidSQL(colname, "colname")))
 			} else {
-				sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s = %s", ValidSQL(colname, "colname"), ValidSQL(val, "colvalue")))
+				if IsNumeric(val) {
+					sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s = %s", ValidSQL(colname, "colname"), ValidSQL(val, "colvalue")))
+				} else {
+					sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s = '%s'", ValidSQL(colname, "colname"), ValidSQL(val, "colvalue")))
+				}
 			}
 		}
 
@@ -862,19 +902,23 @@ func ValidSQL(input, mode string) string {
 		reg := regexp.MustCompile(`[^a-zA-Z0-9_\.]`)
 		return reg.ReplaceAllString(input, "")
 	case "colvalue":
-		// For column values, escape single quotes
-		return strings.ReplaceAll(input, "'", "''")
+		// For column values, escape single quotes and backslashes
+		// Note: Backslashes must be escaped first, then single quotes
+		result := strings.ReplaceAll(input, "\\", "\\\\")
+		result = strings.ReplaceAll(result, "'", "''")
+		return result
 	case "select":
 		// For SELECT clauses, be more permissive but still safe
-		// Remove semicolons and common SQL injection patterns
-		dangerous := []string{";", "--", "/*", "*/", "xp_", "sp_", "DROP ", "DELETE ", "TRUNCATE ", "UPDATE ", "INSERT "}
-		result := input
-		for _, d := range dangerous {
-			result = strings.ReplaceAll(result, d, "")
-			result = strings.ReplaceAll(result, strings.ToLower(d), "")
-			result = strings.ReplaceAll(result, strings.ToUpper(d), "")
+		// Remove semicolons and common SQL injection patterns (case-insensitive)
+		dangerous := []string{
+			";", "--", "/\\*", "\\*/", "xp_", "sp_",
+			"drop ", "delete ", "truncate ", "update ", "insert ",
+			"exec ", "execute ", "union ", "declare ", "alter ", "create ",
 		}
-		return result
+		// Build a single regex pattern with all dangerous keywords
+		pattern := "(?i)(" + strings.Join(dangerous, "|") + ")"
+		re := regexp.MustCompile(pattern)
+		return re.ReplaceAllString(input, "")
 	default:
 		return input
 	}