数据库删除问题

Question

 

            if (dataGridView1.CurrentCell!= null)

            {

                string str = "select JobName from Table2 where JoblD=" + ds.Tables[0].Rows[dataGridView1.CurrentRow.Index][0].ToString().Trim()+ "and JoblD not in (select distinct Table2.JobName from Table3 inner join Table2 on Table3.JobName = Table2.JobName)";

                SqlCommand com=new SqlCommand (str,con);

                SqlDataReader dr;

                dr = com.ExecuteReader();

                if (!dr.Read())

                {

                    MessageBox.Show("删除工种'" + ds.Tables[0].Rows[dataGridView1.CurrentCell.RowIndex][1].ToString().Trim() + "'失败,请先删除与此工种的相关员工", "消息", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);

                    dr.Close();

                }

            }

出现错误为，无法将表2中的inverchar "JobName"字段转换为INT型,是不是我写错了什么?怎么看都没错额.....

Answer 1

请仔细看我下划线加粗的部分！

  string str = "select JobName from Table2 where JoblD=" + ds.Tables[0].Rows[dataGridView1.CurrentRow.Index][0].ToString().Trim()+ "and JoblD not in (select distinct Table2.JobName from Table3 inner join Table2 on Table3.JobName = Table2.JobName)";

你怎么可以把jobId和JobName相比较呢？

建议把第二个下划线部分改成：

Table2.JobId

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Answer 2

因为JoblD类型为int，JobName类型为nvarchar

1. string str = "select JobName from Table2 where JoblD=" + ds.Tables[0].Rows[dataGridView1.CurrentRow.Index][0].ToString().Trim()+ "and JoblD not in (select distinct Table2.JobID from Table3 inner join Table2 on Table3.JobName = Table2.JobName)";
2. string str = "select JobName from Table2 where JoblD=" + ds.Tables[0].Rows[dataGridView1.CurrentRow.Index][0].ToString().Trim()+ "and JobName not in (select distinct Table2.JobName from Table3 inner join Table2 on Table3.JobName = Table2.JobName)";

看需求，请自取一个

另外，好像没看到有Delete语句(似乎不太符合题意？)

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