Database Functions

The library supplies implementations for several common database functions. We do not try to implement a large set of functions. Rather, we supply some common functions as examples and make it relatively easy to write your own implementations of functions you might want to use that are not supplied by the library. See the page “Extending the Library” for information about how to write your own functions.

The supplied functions are all in the package. In addition, there are static methods in the SqlBuilder to access all functions.

In the following table…

  • “Function Class” is implementing class in the package
  • “Example” shows the static method from the SqlBuilder class
  • “Rendered Result” shows the rendered SQL fragment generated by the function
Function Class Example Rendered Result
Add add(column1, column2, constant(55)) column1 + column2 + 55
Concatenate concatenate(stringConstant("Name: ", column1) 'Name: ' || column1
Divide divide(column1, column2, constant(55)) column1 / column2 / 55
Lower lower(column1) lower(column1)
Multiply multiply(column1, column2, constant(55)) column1 * column2 * 55
OperatorFunction applyOperator(“^”, column1, column2) column1 ^ column2
Substring substring(column1, 5, 7) substring(column1, 5, 7)
Subtract subtract(column1, column2, constant(55)) column1 - column2 - 55
Upper upper(column1) upper(column1)

Note especially the OperatorFunction - you can use this function to easily implement operators supported by your database. For example, MySQL supports a number of bitwise operators that can be easily implemented with this function.