Question

我有一个包含2个嵌入子表单的表单。

subform_1上的on-click事件从所选的subform_1记录（所有TEXT字段）中设置引用5 attrs的subform_2的记录源。

strSQL = "SELECT Table_1.* FROM Table_1 " & _
    "WHERE (((Table_1.Attr_A)= '" & Forms![mainform]![subform_1]![attr1] & "') " & _
    "AND ((Table_1.Attr_B) = '" & Forms![mainform]![subform_1]![attr2] & "') " & _
    "AND ((Table_1.Attr_C) = '" & Forms![mainform]![subform_1]![attr3] & "') " & _
    "AND ((Table_1.Attr_D) = '" & Forms![mainform]![subform_1]![attr4] & "') " & _
    "AND ((Table_1.Attr_E) = '" & Forms![mainform]![subform_1]![attr5] & "'));"
Forms![mainform]![subform_2].Form.RecordSource = strSQL

我的问题是，有些记录在5个必需的attrs中可能有一个NULL值，这是一个有效的条件。周围的＆＃39;＆＃39;当subform_1值为NULL时，会在集合中生成（0）记录。

有效处理subform_1中的NULL条件的任何建议吗？

Answer 1

如果你只考虑Table_1.Attr_A，我认为你说你想要这个......

"SELECT t1.* FROM Table_1 AS t1 " & _
"WHERE (t1.Attr_A & '') = '" & Forms![mainform]![subform_1]![attr1] & "'"

如果这是正确的，请根据AND为下一个条件添加Attr_B。

"SELECT t1.* FROM Table_1 AS t1 " & _
"WHERE " & _
"(t1.Attr_A & '') = '" & Forms![mainform]![subform_1]![attr1] & "'" & _
" AND (t1.Attr_B & '') = '" & Forms![mainform]![subform_1]![attr2] & "'"

然后通过添加剩余条件继续。

Answer 2

我相信Nz函数也可以使用：

"SELECT t1.* FROM Table_1 AS t1 " & _
"WHERE Nz(t1.Attr_A) = '" & Forms![mainform]![subform_1]![attr1] & "'"

MS Access：Null vs'' - 让我发疯

2 个答案: