ColumnTransformer (Hibernate JavaDocs)

```
@Target({FIELD,METHOD})
@Retention(RUNTIME)
@Repeatable(ColumnTransformers.class)
public @interface ColumnTransformer
```
Specifies custom SQL expressions used to read and write to the column mapped by the annotated persistent attribute in all generated SQL involving the annotated persistent attribute.
- A write() expression must contain exactly one JDBC-style '?' placeholder.
- A read() expression may not contain JDBC-style placeholders.
For example:
```
 {@code
```
See Also:

ColumnTransformers

Optional Element Summary

Optional Elements
Modifier and Type	Optional Element	Description
`String`	`forColumn`	The name of the mapped column, if a persistent attribute maps to multiple columns.
`String`	`read`	A custom SQL expression used to read from the column.
`String`	`write`	A custom SQL expression used to write to the column.

- Element Detail
  - forColumn
```
String forColumn
```
    The name of the mapped column, if a persistent attribute maps to multiple columns. Optional if a persistent attribute is mapped to a single column
    
    Default:
    
    ""
- - read
```
String read
```
    A custom SQL expression used to read from the column.
    
    Default:
    
    ""
- - write
```
String write
```
    A custom SQL expression used to write to the column. The expression must contain exactly one JDBC-style '?' placeholder.
    
    Default:
    
    ""