Simple analysis of C # binding variables and anonymous blocks getting the current value of a sequence

We'll talk about C # binding variables and anonymous blocks to get the current value of the sequence, we first need to do a series of operations in Oracle, followed by the concrete operation of C # binding variables.

1. Create tables, sequences, triggers in Oracle:

SQL>　create　table　TESTTAB
(
　　ID　　　NUMBER,
　　NAME　VARCHAR2(10)
);

Table is created

SQL>　create　sequence　TESTTABSEQ
　　　　minvalue　1
　　　　maxvalue　999999999999999999999999999
　　　start　with　1
　　　　increment　by　1
　　　　cache　20;

Sequence is created

SQL>　create　or　replace　trigger　Tr_testtabid
　　　before　insert　on　testtab　for　each　row

　　　　begin
　　　　　SELECT　TESTTABSEQ.NEXTVAL　into　:NEW.id　from　dual;
　　　　　end　Tr_testtabid;
　　　　/

Triggers are created

2. Main C # binding variable code:

using　ORAC　=　System.Data.OracleClient;
private　void　button1_Click(object　sender,　System.EventArgs　e)
{
　try
　{

　　string　str_Sql　=　@"begin　insert　into　testtab(name)　values('test');　select　TESTTABSEQ.Currval　into　:ID　from　dual;　end;";
　　ORAC.OracleCommand　cmd=　new　ORAC.OracleCommand(str_Sql,this.oracleConnection1);

　　ORAC.OracleParameter　parm　=　new　ORAC.OracleParameter("ID",ORAC.OracleType.Number);
　　parm.Direction　=　ParameterDirection.Output;
　　cmd.Parameters.Add(parm);

　　if(this.oracleConnection1.State　==　System.Data.ConnectionState.Closed)
　　{
　　　this.oracleConnection1.Open();
　　}
　　cmd.ExecuteNonQuery();

　　this.textBox1.Text　=　cmd.Parameters[0].Value.ToString();
　}
　catch(Exception　ex)
　{
　　MessageBox.Show("发生错误！";

　}
　finally
　{
　　this.oracleConnection1.Close();
　}

}