1 try

<try>
    <body /> !
    <catch /> !
</try>

Remarks

The code lines could cause an exception must be contained between the start and end mark of the label <body>. The set of actions to execute, if an exception is produced, has to be inside of the tag <catch>.

Example
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[...]
<try>
    <body>
        <connection.begin />
        <select prefix='m_'>
            <columns>COUNT(*) cnt</columns>
            <from table='gcommovd'>
                <join table='galmctas' alias='a'>
                    <on>gcommovd.ctaori = a.code</on>
                </join>
                <join table='galmctas' alias='b'>
                    <on>gcommovd.ctades = b.code</on>
                </join>
            </from>
            <where>
                gcommovd.code = <m_tipdoc/> AND
                a.indsal != 'N' AND
                b.indsal != 'N'
            </where>
        </select>
        [...]
        <execute-procedure name='gcommovh'>
            <in>
                <select>
                    <columns>rowid</columns>
                    <from table='gcommovh' />
                    <where>cabid = <m_cabtra/></where>
                </select>
            </in>
        </execute-procedure>
        <connection.commit />
    </body>
    <catch>
        <connection.rollback />
        <insert table='tmp_plan_err' columns='errmsg'>
             <value><error.message/></value>
        </insert>
    </catch>
</try>
[...]

This example code shows a case of transactions use through the sentence <try>. The set of lines that could cause an exception, starts with the start transaction senetence <connection.begin>. In the case of that an unexpected situation between the start and end mark of the label <body>, the block of actions contained in the tag <catch> is executed. This block begans with the element <connection.rollback>, undoing the changes that were performed from the start of the transaction until the instruction that causes the exception.