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Document type inference issues with dynamic params in SQL (#10801) 

* Clarify docs

* Apply suggestions from code review

Co-authored-by: Charles Smith <38529548+techdocsmith@users.noreply.github.com>

Co-authored-by: Charles Smith <38529548+techdocsmith@users.noreply.github.com>
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Atul Mohan 2021-03-04 05:48:11 -06:00 committed by GitHub
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docs/querying/sql.md
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@ -219,6 +219,18 @@ at execution time. To use dynamic parameters, replace any literal in the query w
corresponding parameter value when you execute the query. Parameters are bound to the placeholders in the order in
which they are passed. Parameters are supported in both the [HTTP POST](#http-post) and [JDBC](#jdbc) APIs.
In certain cases, using dynamic parameters in expressions can cause type inference issues which cause your query to fail, for example:
```sql
SELECT * FROM druid.foo WHERE dim1 like CONCAT('%', ?, '%')
```
To solve this issue, explicitly provide the type of the dynamic parameter using the `CAST` keyword. Consider the fix for the preceding example:
```
SELECT * FROM druid.foo WHERE dim1 like CONCAT('%', CAST (? AS VARCHAR), '%')
```
## Data types
### Standard types