plsql 条件where之后的判断不理解，哪位高手可以释惑！

Question

存储过程如下：
procedure p_init_report_daysum(in_daitemsn in varchar2,
in_databatch in varchar2) is
v_SQLTXT varchar2(4000);
begin

v_SQLTXT := 'delete from report_diff_daysum
where data_batch >= :1 //这个>=:1是什么意思？
and daitem_sn = :2 ';
execute immediate v_SQLTXT
using in_databatch, in_daitemsn;

/* v_SQLTXT := 'delete from report_ds_daysum
where data_batch >= ' :1 '
and daitem_sn = ' :2 '';
execute immediatev_v_SQLTXT
using in_databatch, in_daitemsn;*/

v_SQLTXT := 'delete from report_das_score
where data_batch >= :1
and daitem_sn = :2 ';
execute immediate v_SQLTXT
using in_databatch, in_daitemsn;
end;

where条件之后的>=:1是什么意思？

Answer 1

where data_batch >= :1 当数据量大于一条时候执行 :=是plsql的语法特点