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Docs for the cast_keep_nullable setting (English).
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Default value: `120`.
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## cast_keep_nullable {#cast_keep_nullable}
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Enables or disables converstion to nullable types for [CAST](../../sql-reference/functions/type-conversion-functions.md#type_conversion_function-cast) operator.
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If set, `CAST(something_nullable AS Type)` returns `Nullable(Type)`.
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Possible values:
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- 0 — Nullable type converstion disabled.
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- 1 — Nullable type converstion enabled.
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Default value: `0`.
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**Examples**
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Query with nullable type converstion disabled:
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```sql
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SET cast_keep_nullable = 0;
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SELECT CAST(toNullable(toInt32(0)) AS Int32) as x, toTypeName(x);
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```
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Result:
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```
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┌─x─┬─toTypeName(CAST(toNullable(toInt32(0)), 'Int32'))─┐
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│ 0 │ Int32 │
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└───┴───────────────────────────────────────────────────┘
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```
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Query with nullable type converstion enabled:
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```sql
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SET cast_keep_nullable = 1;
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SELECT CAST(toNullable(toInt32(0)) AS Int32) as x, toTypeName(x);
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```
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Result:
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```
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┌─x─┬─toTypeName(CAST(toNullable(toInt32(0)), 'Int32'))─┐
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│ 0 │ Nullable(Int32) │
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└───┴───────────────────────────────────────────────────┘
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```
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**See Also**
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- [CAST](../../sql-reference/functions/type-conversion-functions.md#type_conversion_function-cast) operator
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[Original article](https://clickhouse.tech/docs/en/operations/settings/settings/) <!-- hide -->
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