Then in the second table I have select ..., null as opt from... I know that I could have an empty string with '' as opt however, I don't want an empty string, I really do need it to be null.
select a,b,null,null from table1 union select null,null,c,d from table2 union select null,null,null,null,e,f from table3.
Union select null, null, null, null, null, null, null from information_schema.tables. for a small database containing three tables. this instruction is used in sql injection I tried it and it worked but I didn't really know how it works can somebody help me...
2018-12-04 {\x22visitorId\x22: null, \x22pageSize\x22: 36, \x... 2018-12-04 i \x63\x61nt ti\x65n ti\x65n 2018-12-04 \x2f\x01\x69\163\151\x62\x69\154it\171 2018-12-04 \x65m ko th\x65 \.
union all select null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null
Union select null, null, null, null, null, null -- test all nulls --*/ ). A. DECLARE @ColumnDynamicSQL nvarchar(MAX)
A field with a NULL value is a field with no value. If a field in a table is optional, it is possible to insert a new record or update a record without adding a value to this field.
In R language, NULL … Continue reading R null values: NULL, NA, NaN, Inf.