How to Solve Oracle ORA-01795 Error: Too Many Expressions in IN Clause?

Overcoming ORA-01795 Error: Maximum Expressions in a List

The ORA-01795 error arises when a query attempts to specify more than 1000 expressions within an IN clause. This can occur when selecting data from a table based on a large number of values.

To address this issue, multiple IN clauses can be employed as a workaround. The modified query would split the values into smaller groups, utilizing multiple IN clauses to query the data in chunks.

For instance, consider the following example:

select field1, field2, field3 
from table1 
where name in 
(
'value1',
'value2',
...
'value10000+'
);

This query would result in the ORA-01795 error due to the excessive number of expressions in the IN clause. To resolve this, the query can be rewritten using multiple IN clauses:

select field1, field2, field3 from table1 
where  name in ('value1', 'value2', ..., 'value999') 
    or name in ('value1000', ..., 'value1999') 
    or ...;

By dividing the values into smaller groups and using multiple IN clauses, the query can effectively bypass the 1000 expression limit and retrieve the desired data.

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