C#ºÍSQL

SQL code:
update users set user_money='100' where user_id=1

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C# code:

public int Deposit(int userid, int money)
{
UserVO uservo = new UserVO(userid);
float moneySum = Convert.ToSingle(money.ToString()) + uservo.userMoney;
string cmdText = "update users set user_money='" + moneySum + "' where user_id=" + userid;
int flag = 0;
flag = connDB.Flag(cmdText);
return flag;

}


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string cmdText = "update users set user_money=" + moneySum + " where user_id=" + userid;

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string cmdText = "update users set user_money="+ moneySum +" where user_id=" + userid;
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string cmdText = "update users set user_money=" + moneySum + " where user_id=" + userid;

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string cmdText
= "update users set user_money='" + moneySum + "' where [user_id]=" + us