如何使用上线了app建设网站vs2008 手机网站开发

前言

在达梦数据库的使用过程中尽管管理工具很好用，但是命令行工具还是有着得天独厚的优势，但是在参数绑定方面就没有管理工具做的更加完美，现在就汇总下disql 工具参数绑定的常用几种方式

disql 参数绑定

使用 ?

select * from v$dm_ini where para_name =? and  para_value=?;
input value of param1:COMPATIBLE_MODEinput value of param2:2LINEID     PARA_NAME       PARA_VALUE MIN_VALUE MAX_VALUE DEFAULT_VALUE MPP_CHK SESS_VALUE FILE_VALUE DESCRIPTION                                                                                     PARA_TYPE
---------- --------------- ---------- --------- --------- ------------- ------- ---------- ---------- ----------------------------------------------------------------------------------------------- ---------
1          COMPATIBLE_MODE 2          0         6         0             Y       2          2          Server compatible mode, 0:none, 1:SQL92, 2:Oracle, 3:MS SQL Server, 4:MySQL, 5:DM6, 6:Teradata  IN FILE

优

1. 无需给考虑给字符串加双引号，即只需要输入参数值就行
2. 查看sqllog 内容如下，是参数绑定后触发执行

[ORA]: select * from v$dm_ini where para_name =? and  para_value=?;^M
[ORA]: select * from v$dm_ini where para_name =? and  para_value=?;^M
Load para: 0 rows^M
PARAMS(SEQNO, TYPE, DATA)={(0, VARCHAR2, 'COMPATIBLE_MODE'), (1, VARCHAR2, '2')}
[SEL] select * from v$dm_ini where para_name =? and  para_value=?;^M
[SEL] select * from v$dm_ini where para_name =? and  para_value=?; EXECTIME: 4(ms) ROWCOUNT: 1(rows).^M

劣

不显示参数名，当参数列表过多时，无法进行区分

使用 &变量名

select * from v$dm_ini where para_name = &para_name and  para_value= &para_value;
input para_name value:'COMPATIBLE_MODE'
input para_value value:2
old value 1:select * from v$dm_ini where para_name = &para_name and  para_value= &para_value;
new value 1:select * from v$dm_ini where para_name = 'COMPATIBLE_MODE' and  para_value= 2;LINEID     PARA_NAME       PARA_VALUE MIN_VALUE MAX_VALUE DEFAULT_VALUE MPP_CHK SESS_VALUE FILE_VALUE DESCRIPTION                                                                                     PARA_TYPE
---------- --------------- ---------- --------- --------- ------------- ------- ---------- ---------- ----------------------------------------------------------------------------------------------- ---------
1          COMPATIBLE_MODE 2          0         6         0             Y       2          2          Server compatible mode, 0:none, 1:SQL92, 2:Oracle, 3:MS SQL Server, 4:MySQL, 5:DM6, 6:Teradata  IN FILE

优

可以显示参数名

劣

1. 该方式实际上类似于参数替换，并没有实现参数绑定效果，查看sqllog

[ORA]: select * from v$dm_ini where para_name = 'COMPATIBLE_MODE' and  para_value= 2;^M
[SEL] select * from v$dm_ini where para_name = 'COMPATIBLE_MODE' and  para_value= 2;^M
[SEL] select * from v$dm_ini where para_name = 'COMPATIBLE_MODE' and  para_value= 2; EXECTIME: 4(ms) ROWCOUNT: 1(rows).

2. 针对字符串需要添加双引号

select * from v$dm_ini where para_name = &para_name and  para_value= &para_value;
input para_name value:COMPATIBLE_MODE
input para_value value:2
old value 1:select * from v$dm_ini where para_name = &para_name and  para_value= &para_value;
new value 1:select * from v$dm_ini where para_name = COMPATIBLE_MODE and  para_value= 2;
select * from v$dm_ini where para_name = COMPATIBLE_MODE and  para_value= 2;
[-2111]:Error in line: 1
Invalid column name [COMPATIBLE_MODE].
used time: 0.382(ms). Execute id is 0.

总结

两种都不是最优，都无法实现预期中绑定参数的情况下动态显示参数名进行参数值输入