List the types of parameter modes

• Formal parameters can have three modes – IN, OUT or IN OUT. The default is IN.
• We can’t change the value of IN parameter, it is considered read-only and cannot be changed, if we do so we got a compilation error.
• Any value the actual parameter has when the procedure is called is ignored. So it has the value of NULL.
• If the procedure raises an exception, the values of IN OUT, OUT format parameters are not copied to their corresponding actual parameters.
• Actual IN, IN OUT parameters must be a variable and cannot be a constant or expression.
• You can read from OUT parameter not prior to 7.3.4 or 8.0.3