IF-ELSE Alternative for Multiple SQL criteria for use in BIRT

问题

I want to create a report by using BIRT. I have 5 SQL criterias as the parameter for the report. Usually when I have 3 criterias, I am using nested if-else for the WHERE statement with javascript.

Since right now I have more criteria it becomes more difficult to write the code and also check the possibilities, especially for debug purposes.

For example the criteria for table employee, having these 5 criterias : age, city, department, title and education. All criteria will be dynamic, you can leave it blank to show all contents.

Do anyone know the alternative of this method?

回答1:

There is a magical way to handle this without any script, which makes reports much easier to maintain! We can use this kind of SQL query:

SELECT *
FROM mytable
WHERE (?='' OR city=? )
AND (?=-1 OR age>? )
AND (?='' OR department=? )
AND (?='' OR title=? )

So each criteria has two dataset parameters, with a "OR" clause allowing to ignore a criteria when the parameter gets a specific value, an empty value or a null value as you like. All those "OR" clauses are evaluated with a constant value, therefore performances of queries can't be affected.

In this example we should have 4 report parameters, 8 dataset parameters (each report parameter is bound to 2 dataset parameters) and 0 script. See a live example of a report using this approach here.

If there are many more criteria i would recommend to use a stored procedure, hence we can do the same with just one dataset parameter per criteria.

Integer parameter handling

If we need to handle a "all" value for an integer column such age: we can declare report parameter "age" as a String type and dataset parameters "age" as an integer. Then, in parameters tab of the dataset use a value expression instead of a "linked to report parameters". For example if we like a robust input which handles both "all" "null" and empty values here is the expression to enter:

(params["age"].value=="all" || params["age"].value=="" || params["age"].value==null)?-1:params["age"].value

The sample report can be downloaded here (v 4.3.1)

回答2:

Depending on the report requirements and audiance you may find this helpful.

Use text box paramaters and make the defualt value % (which is a wild card)

SELECT *
FROM mytable
WHERE city like ? 
  AND age like ?
  AND department like ?
  AND title like ?

This also allows your users to search for partial names. if the value in the city text box is %ville% it would return all the cities with "ville" anyplace in the city name.

回答3:

If report parameters to be included in SQL-WHERE clause would be named according to some naming convention, for instance query_employee_[table column name], you could write Java-Script code in a generic way, so that you will not have to change it when new reporters being added.

for each param in params { if param.name starts with query_employee_ { where_clause += " and " + param.name.substring(after query_employee) + " == '" + param.value + "'"; } }

You will have to check type of a parameter to make a decision whether you have to quote the parameter value.

The event handler could look as follows (implemented in Java, but it should be possible to port it to JavaScript, if you really need it to be in JavaScript):

public class WhereConditionEventHandler extends DataSetEventAdapter {

    @Override
    public void beforeOpen(IDataSetInstance dataSet,
            IReportContext reportContext) throws ScriptException {
        super.beforeOpen(dataSet, reportContext);
        String whereClause = " where 1 = 1 ";
        SlotHandle prms = reportContext.getDesignHandle().getParameters();
        for (int i = 0; i < prms.getCount(); i++) {
            if (prms.get(i) instanceof ScalarParameterHandle) {
                ScalarParameterHandle prm = (ScalarParameterHandle) prms.get(i);
                int n = prm.getName().indexOf("sql_customer_");
                if (n > -1) {
                    String prmValue = "" + reportContext.getParameterValue(prm.getName());
                    if (DesignChoiceConstants.PARAM_TYPE_STRING.equals(prm.getDataType())) {
                        prmValue = "'" + prmValue + "'";
                    }
                    whereClause += " and " + prm.getName().substring("sql_customer_".length()) + " = " + prmValue;
                }
            }
        }
        System.out.println("sql: " + whereClause);
        dataSet.setQueryText(dataSet.getQueryText() + whereClause);
    }
}

By the way, you can pass in parameters that are not registered as report parameters in the BIRT report design. BIRT will nevertheless put them into "params" array.

来源：https://stackoverflow.com/questions/21073182/if-else-alternative-for-multiple-sql-criteria-for-use-in-birt

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sql

if-statement

birt