ORA-00923: FROM keyword not found where expected
PL/SQL developers who run sql queries on Oracle database may experience the "ORA-00923: FROM keyword not found where expected" error.
Although the ORA-00923 error is self describing the Oracle exception, it may be difficult especially for Transact-SQL (T-SQL) developers to solve ORA-00923 error.
For example, if you run following PL/SQL statement to display SysDate variable :
Oracle database developers will experience the error message :
ORA-00923: FROM keyword not found where expected
But if the sql developer has experience on SQL Server T-SQL programming, he will execute following SQL Select statement successfully.
The difference between T-SQL and PL/SQL is PL/SQL developers have to use DUAL dummy table which has single row single column data which is build for such tasks.
If as a developer, you place Dual table name after FROM clause in your PL/SQL Select statement, the query will run successfully.
The correct sql code for PL/SQL developers to use will be as follows:
PL/SQL developers should use Oracle Dual table in order to select system variable or to select data except from Oracle database table.
This is one of the first hints for SQL developers who are new to PL/SQL but have experience on T-SQL programming.
In order to avoid ORA-00923: FROM keyword not found where expected error message, PL/SQL developers can Select system variables, or Select data that does not require an Oracle table FROM Dual table.