把MYSQL中查询出来的NULL转成0
SELECT Tasks.id, name,
TYPE , run_time, template, config, parameters, policy, DATE_FORMAT( create_time, '%%Y-%%m-%%d %%T' ) AS create_time, owner, version, IF( cnt IS NULL ,0,cnt) AS count
FROM Tasks
LEFT JOIN (
SELECT id, COUNT( * ) AS cnt
FROM TaskData
GROUP BY id
)idcount ON Tasks.id = idcount.id
TYPE , run_time, template, config, parameters, policy, DATE_FORMAT( create_time, '%%Y-%%m-%%d %%T' ) AS create_time, owner, version, IF( cnt IS NULL ,0,cnt) AS count
FROM Tasks
LEFT JOIN (
SELECT id, COUNT( * ) AS cnt
FROM TaskData
GROUP BY id
)idcount ON Tasks.id = idcount.id