Added support for expressions as arguments of an IntervalExpression. …

src/main/java/net/sf/jsqlparser/expression/ExpressionVisitorAdapter.java

@@ -326,6 +326,7 @@ public void visit(ExtractExpression expr) {
 
     @Override
     public void visit(IntervalExpression expr) {
+        expr.getParameter().accept(this);
     }
 
     @Override

src/main/java/net/sf/jsqlparser/expression/IntervalExpression.java

@@ -29,14 +29,14 @@
  */
 public class IntervalExpression extends ASTNodeAccessImpl implements Expression {
 
-    private String parameter = null;
+    private Expression parameter = null;
     private String intervalType = null;
 
-    public String getParameter() {
+    public Expression getParameter() {
         return parameter;
     }
 
-    public void setParameter(String parameter) {
+    public void setParameter(Expression parameter) {
         this.parameter = parameter;
     }
 

src/main/java/net/sf/jsqlparser/util/TablesNamesFinder.java

@@ -564,6 +564,7 @@ protected void init(boolean allowColumnProcessing) {
 
     @Override
     public void visit(IntervalExpression iexpr) {
+        iexpr.getParameter().accept(this);
     }
 
     @Override

src/main/java/net/sf/jsqlparser/util/deparser/ExpressionDeParser.java

@@ -721,7 +721,11 @@ public void visit(MultiExpressionList multiExprList) {
 
     @Override
     public void visit(IntervalExpression iexpr) {
-        buffer.append(iexpr.toString());
+            buffer.append("INTERVAL ");
+            iexpr.getParameter().accept(this);
+            if(iexpr.getIntervalType() != null) {
+                buffer.append(" ").append(iexpr.getIntervalType());
+            }
     }
 
     @Override

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -2683,8 +2683,6 @@ Expression PrimaryExpression() #PrimaryExpression:
 
     | LOOKAHEAD(JsonExpression()) retval=JsonExpression()
 
-    | LOOKAHEAD(Function()) retval=Function()
-
     | token=<S_DOUBLE>  { retval = new DoubleValue(token.image); }
 
     | token=<S_LONG> { retval = new LongValue(token.image); }
@@ -2698,7 +2696,9 @@ Expression PrimaryExpression() #PrimaryExpression:
 
     | LOOKAHEAD(2) retval=DateTimeLiteralExpression()
 
-	| LOOKAHEAD(2) retval = IntervalExpression()
+    | LOOKAHEAD(2) retval = IntervalExpression()
+
+    | LOOKAHEAD(Function()) retval=Function()
 
     | retval=Column()
 
@@ -2798,12 +2798,18 @@ JsonExpression JsonExpression() : {
 
 IntervalExpression IntervalExpression() : {
     IntervalExpression interval = new IntervalExpression();
+    Expression item;
+    Expression intermediate;
     Token token;
     boolean signed = false;
 }
 {
-    <K_INTERVAL> ["-" {signed=true;}] (token=<S_LONG> | token=<S_DOUBLE> | token=<S_CHAR_LITERAL>) 
-    { interval.setParameter((signed?"-":"") + token.image); }
+
+     <K_INTERVAL> (LOOKAHEAD(ConcatExpression()) item = ConcatExpression() 
+                   |LOOKAHEAD("(" ConcatExpression() ")") "(" intermediate=ConcatExpression() ")" {item = new Parenthesis(intermediate); }
+                   |LOOKAHEAD("(" PrimaryExpression() ")") "(" intermediate=PrimaryExpression() ")" {item = new Parenthesis(intermediate); }
+                   | item = PrimaryExpression())
+    { interval.setParameter(item); }
     [ LOOKAHEAD(2) token = <S_IDENTIFIER> { interval.setIntervalType(token.image); } ]
     {
         return interval;

src/test/java/net/sf/jsqlparser/statement/select/SelectTest.java

@@ -2103,7 +2103,7 @@ public void testInterval2() throws JSQLParserException {
         assertTrue(sub.getRightExpression() instanceof IntervalExpression);
         IntervalExpression iexpr = (IntervalExpression) sub.getRightExpression();
 
-        assertEquals("'45 MINUTE'", iexpr.getParameter());
+        assertEquals("'45 MINUTE'", iexpr.getParameter().toString());
     }
 
     @Test
@@ -2118,6 +2118,12 @@ public void testInterval4() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed(stmt);
     }
 
+    @Test
+    public void testInterval5() throws JSQLParserException {
+        String stmt = "SELECT INTERVAL (UNIX_TIMESTAMP(CAST('2018-12-03 19:40:00' AS DATETIME)) / 300) * 300 SECOND";
+        assertSqlCanBeParsedAndDeparsed(stmt);
+    }
+
     @Test
     public void testInterval5_Issue228() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed("SELECT ADDDATE(timeColumn1, INTERVAL 420 MINUTES) AS timeColumn1 FROM tbl");