[英]How to update multiple fields in a table if one them might be blank?
我想在名為Personnel-table
的表中更新5
個用戶個人信息字段。
用戶可能希望更新所有字段,部分字段或根本不更新。
用戶可能想要更新的字段是: FirstName
, LastName
, Password
, UserName
和Address
。
該代碼執行此操作:
public boolean updateUserInfo(String _idnumber , String _usernameNew , String _passwordNew ,
String _addressNew , String _firstNameNew , String _lastNameNew) throws SQLException
{
ResultSet resultSet = null;
String sqlStatement = "UPDATE PersonnelTable set `UserName` = ? WHERE `IdNumber` = ?";
this.m_prepared = (PreparedStatement) this.m_connection.prepareStatement(sqlStatement);
this.m_prepared.executeUpdate("USE Personnel");
// set the ID number & account number
/**
* first
*/
m_prepared.setString(1, _usernameNew);
m_prepared.setString(2, _idnumber);
// execute first query - update password
if (_usernameNew!= "")
{
resultSet = m_prepared.executeQuery();
return true;
}
/**
* Second
*/
sqlStatement = "UPDATE PersonnelTable set `FirstName` = ? WHERE `IdNumber` = ?";
this.m_prepared = (PreparedStatement) this.m_connection.prepareStatement(sqlStatement);
m_prepared.setString(1, _firstNameNew);
m_prepared.setString(2, _idnumber);
if (_firstNameNew != "")
{
resultSet = m_prepared.executeQuery();
return true;
}
/**
* Third
*/
sqlStatement = "UPDATE PersonnelTable set `LastName` = ? WHERE `IdNumber` = ?";
this.m_prepared = (PreparedStatement) this.m_connection.prepareStatement(sqlStatement);
m_prepared.setString(1, _lastNameNew);
m_prepared.setString(2, _idnumber);
if (_lastNameNew!= "")
{
resultSet = m_prepared.executeQuery();
return true;
}
/**
* Fourth
*/
sqlStatement = "UPDATE PersonnelTable set `Address` = ? WHERE `IdNumber` = ?";
this.m_prepared = (PreparedStatement) this.m_connection.prepareStatement(sqlStatement);
m_prepared.setString(1, _addressNew);
m_prepared.setString(2, _idnumber);
if (_addressNew!= "")
{
resultSet = m_prepared.executeQuery();
return true;
}
/**
* Fifth
*/
sqlStatement = "UPDATE PersonnelTable set `Password` = ? WHERE `IdNumber` = ?";
this.m_prepared = (PreparedStatement) this.m_connection.prepareStatement(sqlStatement);
m_prepared.setString(1, _passwordNew);
m_prepared.setString(2, _idnumber);
if (_passwordNew!= "")
{
resultSet = m_prepared.executeQuery();
return true;
}
return false;
}
但正如您所看到的,代碼太大了,因為我運行了5次查詢。
如何告訴mysql如果每個字段都不是空字符串""
,那么在一個mysql查詢中更新所需的字段? 是可能的還是我必須每次都這樣做?
問候
您可以在單個查詢中輕松執行此操作:
UPDATE PersonnelTable
SET FirstName = IF(? <> "", ?, FirstName),
LastName = IF(? <> "", ?, LastName),
Password = IF(? <> "", ?, Password),
UserName = IF(? <> "", ?, UserName),
Address = IF(? <> "", ?, Address)
WHERE IdNumber = ?;
如果您的字段可以有像空值""
那么你可以使用IF(? IS NOT NULL, ?, field_name)
而不是空白。
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