我正在尝试使用Delphi XE3和Zeos 7.0.4在MySQL 5.6中保留两个具有主从关系的表。当我在主服务器上执行ApplyUpdates时,自动增量字段的值保持为0。我需要自动增量值,因此我可以将详细信息表与来自ApplyUpdates的主表的ID字段进行链接。我正在使用带有AutoCommit = FALSE和TransactionIsolationLevel = tiReadCommitted的ZConnection,带有CachedUpdates = TRUE的ZQuery。我想念什么?
ZQPerson.Append;
ZQEmployee.Append;
try
ZQPersonName.Value := Edit1.Text;
ZQPerson.ApplyUpdates; //Here I expected to have the auto increment value on the Id field of ZQPerson, but it returns always 0
ZQEmployeePersonID.Value := ZQPersonId.Value; //Here I'd link Employee to it's Person record
ZQEmployeeRegNo.Value := StrToInt(Edit2.Text);
ZQEmployee.ApplyUpdates;
ZConnection1.Commit; //Here I would persist both tables in a single transaction to avoid master table without details
except
ZQPerson.CancelUpdates;
ZQEmployee.CancelUpdates;
ZConnection1.Rollback; //In case of exceptions rollback everything
raise;
end;
ZQPerson.CommitUpdates;
ZQEmployee.CommitUpdates;
我的ZSQLMonitor跟踪是这样:
2013-08-29 00:01:23 cat: Execute, proto: mysql-5, msg: INSERT INTO person (Id, name) VALUES (NULL, 'Edit1') --> This is just after ZQPerson.ApplyUpdates
2013-08-29 00:01:50 cat: Execute, proto: mysql-5, msg: INSERT INTO employee (Id, RegNo, ProductId) VALUES (NULL, 1000, 0), errcode: 1452, error: Cannot add or update a child row: a foreign key constraint fails (`test`.`employee`, CONSTRAINT `FK_A6085E0491BDF8EE` FOREIGN KEY (`PersonId`) REFERENCES `person` (`Id`) --> This is just after ZQEmployee.ApplyUpdates
2013-08-29 00:02:05 cat: Execute, proto: mysql-5, msg: Native Rollback call --> Rollback after Exception on the ZQEmployee.ApplyUpdates
您是否使用ZConnection1.StartTransaction开始事务?我也认为您必须在调用ZQuery1.ApplyUpdates之后获取新的id-
后刷新ZQuery1。阅读您的评论,您必须在没有where子句的情况下进行select *?对?我可以建议您使用这种方法:
1)选择并增加当前自动增加值2)从主表中选择id = [step1 id] // //当然是空的3)在步骤1中使用ID添加详细信息4)在主数据集中分配ID5)应用两个更新
我发现的解决方法就是这个。它不能完全满足我的需要,因为它不能透明地使用数据库的自动增量功能,因此可以使用Last_Insert_ID()函数。我正在与zeos开发人员联系以进行检查。
function LastInsertID(ATableName: string): Integer;
var DBQuery: TZQuery;
begin
DBQuery := TZQuery.Create(Self);
with DBQuery do
begin
Connection := ZConnection1;
SQL.Clear;
SQL.Add('Select Last_Insert_ID() as Last_Insert_ID from ' + ATableName);
Open;
Result := FieldByName('Last_Insert_ID').Value;
Free;
end;
end;
procedure Persist;
var LastID: Integer;
begin
ZQPerson.Append;
ZQEmployee.Append;
try
ZQPersonName.Value := Edit1.Text;
ZQPerson.ApplyUpdates; // Here I expected to have the auto increment value on the Id field of ZQPerson, but it returns always 0
LastID := LastInsertID('Person'); //Getting the Last_Insert_ID(), even on the uncommitted transction, works
ZQEmployeePersonId.Value := LastID; //Link the two tables using the Last_Insert_ID() result
ZQEmployeeRegNo.Value := StrToInt(Edit2.Text);
ZQEmployee.ApplyUpdates;
ZConnection1.Commit; // Here I persist both tables in a single transaction to avoid master table without details
except
ZQPerson.CancelUpdates;
ZQEmployee.CancelUpdates;
ZConnection1.Rollback; // In case of exceptions rollback everything
raise;
end;
ZQPerson.CommitUpdates;
ZQEmployee.CommitUpdates;
我在一个简单的数据库中对其进行了测试,该数据库中有两个主表和明细表,这些表嵌套在TDataSource中,并与明细表的where
相关联:
object conMysql: TZConnection
TransactIsolationLevel = tiReadCommitted
object zqryMaster: TZQuery
Connection = conMysql
SQL.Strings = (
'select * from temp.master')
object dsNestedMaster: TDataSource
DataSet = zqryMaster
object zqryDetail: TZQuery
Connection = conMysql
SQL.Strings = (
'select * from temp.detail'
'where id_master =: id')
启动事务后,如果发生错误,所有更新必须等待确认或回滚:
try
zqryMaster.Connection.StartTransaction;
zqryMaster.Edit;
zqryDetail.Edit;
zqryMaster.FindField('dt_mov').Value := Now;
while not zqryDetail.Eof do
begin
zqryDetail.Edit;
zqryDetail.FindField('dt_mov').Value := Now;
zqryDetail.ApplyUpdates;
zqryDetail.Next;
//raise Exception.Create('simple error'); //use for tests, check database after perform
end;
zqryMaster.ApplyUpdates;
zqryMaster.Connection.Commit;
except
zqryMaster.Connection.Rollback;
zqryMaster.CancelUpdates;
zqryDetail.CancelUpdates;
end;