SELECT DISTINCT underling.organization.theBoss 

               FROM gangster underling 

               WHERE underling.name = ?1 OR underling.nickName = ?1 

            ]]>

Listing 9 14, The ejb jar.xml Query Declaration 

EJB QL is similar to SQL but has some surprising differences. The following are some 

important things to note about EJB QL: 

EJB QL is a typed language, meaning that it only allows comparison of like types 

(i.e., strings can only be compared with strings). 

In an equals comparison a variable (single valued path) must be on the left hand side. 

Some examples follow:

 7

g.hangout.state =  CA  

Legal 

 CA  = g.shippingAddress.state 

NOT Legal 

 CA  =  CA  

NOT Legal 

(r.amountPaid * .01) > 300 

NOT Legal 

r.amountPaid > (300 / .01) 

Legal 

Parameters use a base 1 index like java.sql.PreparedStatement. 

Parameters are only allowed on the right hand side of a comparison.  For example: 

gangster.hangout.state = ?1 

Legal 

?1 = gangster.hangout.state 

NOT Legal 

Datetime variables (simgle valued paths) are only allowed to use the > and < 

operators and EJB QL does not have datetime literals.  For example: 

someEntity.datetimeField > ?1 

Legal 

someEntity.datetimeField >= ?1 

NOT Legal 

someEntity.datetimeField BETWEEN ?1 AND ?2 

NOT Legal 

someEntity.datetimeField > ?1 AND someEntity.datetimeField < ?2 

Legal 

7

 The example "(r.amountPaid * .01) > 300" is presented on page 244 of "Enterprise JavaBeans 3

rd

 Edition" by Richard Monson Haefel to 

demonstrate the use of arithmetic operators in a WHERE clause, and is included here to highlight the fact that it is not legal EJB QL syntax. 

96