SELECT 
    MSP_TEXT_FIELDS.PROJ_ID, 
    MSP_TEXT_FIELDS.TEXT_REF_UID AS TASK_UID, 
    MSP_TEXT_FIELDS.TEXT_VALUE
FROM 
    MSP_TEXT_FIELDS 
        INNER JOIN MSP_CONVERSIONS ON 
            MSP_TEXT_FIELDS.TEXT_FIELD_ID = MSP_CONVERSIONS.CONV_VALUE
WHERE 
    MSP_CONVERSIONS.CONV_STRING="Task Text1";