Fix \\ handling in REGEXP_REPLACE() in Oracle mode

h2/src/main/org/h2/expression/Function.java

@@ -1430,6 +1430,10 @@ public class Function extends Expression implements FunctionCall {
                                     sb.append('$');
                                     continue;
                                 }
+                                if (c == '\\') {
+                                    sb.append('\\');
+                                    i++;
+                                }
                             }
                         }
                         sb.append(c);

h2/src/test/org/h2/test/scripts/functions/string/regex-replace.sql

@@ -26,6 +26,12 @@ select regexp_replace('first last', '(\w+) (\w+)', '\2 \1') as X from dual;
 > last first
 > rows: 1
 
+select regexp_replace('first last', '(\w+) (\w+)', '\\2 \1') as X from dual;
+> X
+> --------
+> \2 first
+> rows: 1
+
 select regexp_replace('first last', '(\w+) (\w+)', '$2 $1') as X from dual;
 > X
 > -----