A simple expression can be a column, pseudocolumn, constant, sequence number, or NULL.
The syntax of a simple expression is as follows:
{ [ query_name.
| [schema.]
{ table. | view. | materialized view. }
] { column | ROWID }
| ROWNUM
| string
| number
| sequence. { CURRVAL | NEXTVAL }
| NULL
}
In addition to the user schema, schema can also be "PUBLIC" with double quotation marks ("). A "PUBLIC" schema specifies a table or view.
Notice
- PUBLIC can be used as a public synonym only in Data Manipulation Language (DML) statements. In Data Definition Language (DDL) statements, it cannot be used as a public synonym.
NCHARandNVARCHAR2are not valid pseudocolumn data types.
The following examples are valid simple expressions:
employees.first_name'welcome to OceanBase'103*3