Amazon Redshift will no longer support the creation of new Python UDFs starting Patch 198. Existing Python UDFs will continue to function until June 30, 2026. For more information, see the [ blog post ](https://aws.amazon.com/blogs/big-data/amazon-redshift-python-user-defined-functions-will-reach-end-of-support-after-june-30-2026/). 

# WHERE clause
<a name="r_WHERE_clause"></a>

The WHERE clause contains conditions that either join tables or apply predicates to columns in tables. Tables can be inner-joined by using appropriate syntax in either the WHERE clause or the FROM clause. Outer join criteria must be specified in the FROM clause. 

## Syntax
<a name="r_WHERE_clause-synopsis"></a>

```
[ WHERE condition ]
```

## *condition*
<a name="r_WHERE_clause-synopsis-condition"></a>

Any search condition with a Boolean result, such as a join condition or a predicate on a table column. The following examples are valid join conditions: 

```
sales.listid=listing.listid
sales.listid<>listing.listid
```

The following examples are valid conditions on columns in tables: 

```
catgroup like 'S%'
venueseats between 20000 and 50000
eventname in('Jersey Boys','Spamalot')
year=2008
length(catdesc)>25
date_part(month, caldate)=6
```

Conditions can be simple or complex; for complex conditions, you can use parentheses to isolate logical units. In the following example, the join condition is enclosed by parentheses. 

```
where (category.catid=event.catid) and category.catid in(6,7,8)
```

## Usage notes
<a name="r_WHERE_clause_usage_notes"></a>

You can use aliases in the WHERE clause to reference select list expressions. 

You can't restrict the results of aggregate functions in the WHERE clause; use the HAVING clause for this purpose. 

Columns that are restricted in the WHERE clause must derive from table references in the FROM clause. 

## Example
<a name="r_SELECT_synopsis-example"></a>

The following query uses a combination of different WHERE clause restrictions, including a join condition for the SALES and EVENT tables, a predicate on the EVENTNAME column, and two predicates on the STARTTIME column. 

```
select eventname, starttime, pricepaid/qtysold as costperticket, qtysold
from sales, event
where sales.eventid = event.eventid
and eventname='Hannah Montana'
and date_part(quarter, starttime) in(1,2)
and date_part(year, starttime) = 2008
order by 3 desc, 4, 2, 1 limit 10;

eventname    |      starttime      |   costperticket   | qtysold
----------------+---------------------+-------------------+---------
Hannah Montana | 2008-06-07 14:00:00 |     1706.00000000 |       2
Hannah Montana | 2008-05-01 19:00:00 |     1658.00000000 |       2
Hannah Montana | 2008-06-07 14:00:00 |     1479.00000000 |       1
Hannah Montana | 2008-06-07 14:00:00 |     1479.00000000 |       3
Hannah Montana | 2008-06-07 14:00:00 |     1163.00000000 |       1
Hannah Montana | 2008-06-07 14:00:00 |     1163.00000000 |       2
Hannah Montana | 2008-06-07 14:00:00 |     1163.00000000 |       4
Hannah Montana | 2008-05-01 19:00:00 |      497.00000000 |       1
Hannah Montana | 2008-05-01 19:00:00 |      497.00000000 |       2
Hannah Montana | 2008-05-01 19:00:00 |      497.00000000 |       4
(10 rows)
```