### WHERE clause

The WHERE clause Interface is used to define the restriction used to generate a new dataset. The restriction can involve one or more datasets, using standard and/or spatial attributes (vertical tabs). The list of operators supported is adjusted to the type of attributes involved.
The operators <,>,<=,>=,<>,=, LIKE, NOT are used with standard attributes comparison, and the spatial operators such as ST_UNION, ST_INTERSECTION, ST_AREA among others are used to operate over geometric attributes.

To define a restriction based on Attributes follow the steps:

1. Select restriction type on the vertical tab:

- Attribute,

2. Define a restriction by selecting:

1. Property
2. Operator (>, >=, <, <=, = )
3. Value - it can be a property of other dataset or a value among all values of the property chosen.

- Property
- Value

3. Click on to add this combination (property x operator x value) to the Table/SQL tabs bellow.
4. On the frame Table/SQL it is possible to handle the restriction adding more clauses, removing one or all lines, or checking the SQL generated:

1. Check the list of restrictions.
2. Define the connector (and, or, nothing) and the next restriction.
3. Clear all restriction using or only one line using .
4. Optionally, change to SQL tab to see the restriction generated in SQL.

5. Go to the step 1 to define the next part of the restriction as necessary.

To define a restriction based on spatial attributes follow the steps:

1. Select restriction type on the vertical tab:

- Spatial

2. Define a restriction by selecting:

1. Property - geometry attribute of the selected dataset
2. Operator (ST_Contains, ST_Union, ST_Crosses, ...)
3. Layer - select the layer to be confronted with the restriction defined.
4. Use Selected Objects - check this option if the goal is to apply the restriction only over the selected objects in the layer displayed.

3. Click on to add this combination (property x operator x value) to the Table/SQL tabs bellow.
4. On the frame Table/SQL it is possible to handle the restriction adding more clauses, removing or checking the SQL generated:

1. Check the list of restrictions.
2. Define the connector (and, or, nothing) and the next restriction.
3. Clear all restriction using or only one line using .
4. Optionally, change to SQL tab to see the restriction generated in SQL.

5. Go to the step 1 to define the next part of the restriction as necessary.