versioned_docs/version-3.0/sql-manual/sql-functions/conditional-functions/assert-true.md

---
{
    "title": "ASSERT_TRUE",
    "language": "en"
}
---

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### Description
#### Syntax

`BOOLEAN assert_true(BOOLEAN condition, VarcharLiteral errmsg)`

When `condition` is `true`, return `true`. Otherwise throws an error with message `errmsg`.
`errmsg` could only be Literal.

### Example

```sql
mysql> select assert_true(1, "wrong");
+------------------------------------------+
| assert_true(cast(1 as BOOLEAN), 'wrong') |
+------------------------------------------+
|                                        1 |
+------------------------------------------+
1 row in set (0.12 sec)

mysql> select assert_true(1, nullable("wrong"));
ERROR 1105 (HY000): errCode = 2, detailMessage = assert_true only accept constant for 2nd argument
mysql> select assert_true(0, "wrong");
ERROR 1105 (HY000): errCode = 2, detailMessage = (10.16.10.8)[INVALID_ARGUMENT][E33] wrong
mysql> select assert_true(null, "wrong");
ERROR 1105 (HY000): errCode = 2, detailMessage = (10.16.10.8)[INVALID_ARGUMENT][E33] wrong
```

### Keywords
    ASSERT_TRUE, ASSERT, TRUE