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How to prevent gcc optimizing some statements in C?
In order to make a page dirty (switching on the dirty bit in the page table entry), I touch the first bytes of the page like this:
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How to limit the maximum value of a numeric field in a Django model?
...t the validation in a form. The question of which range of numbers is acceptable is as much a part of the model as is the question of which kind of number is acceptable. I don't want to have to tell every form through which the model is editable, just which range of numbers to accept. This would vi...
Is there any boolean type in Oracle databases?
...efer char(1) because it uses less space. You can check it this way: create table testbool (boolc char(1), booln number(1)); insert into testbool values ('Y', 1 ); select dump(boolc), dump(booln) from testbool; That CHAR is stored: Typ=96 Len=1: 89 and that NUMBER: Typ=2 Len=2: 193,2 At least in 12c...
创建增量同步Oracle物化视图问题 - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
...个表上建立物化视图日志如“CREATE MATERIALIZED VIEW LOG ON T_tablename;”，再到数据库B上创建数据库链接和快速刷新的物化视图如“create materialized view mv_tablename refresh fast on demand start with sysdate next sysdate+1/288 as select * from T_tablename@dblink_...
Where do you store your salt strings?
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The point of rainbow tables is that they're created in advance and distributed en masse to save calculation time for others - it takes just as long to generate rainbow tables on the fly as it would to just crack the password+salt combination dire...
Does Java read integers in little endian or big endian?
...ch brief published about it long ago. I simply used a 256 element look up table with the bits reversed (table[0x01]=0x80 etc.) after each byte was shifted in from the bit stream.
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MySQL skip first 10 results
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There is an OFFSET as well that should do the trick:
SELECT column FROM table
LIMIT 10 OFFSET 10
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Adding :default => true to boolean in existing Rails column
...ribute == nil ? true : false)) }
Update the migration that created this table, so any future builds of the DB will get it right from the onset. Also run the same process on any deployed-instances of the DB.
If using the "new db migration" method, you can do the update of existing nil-values i...
Alter column, add default constraint
I have a table and one of the columns is "Date" of type datetime. We decided to add a default constraint to that column
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Warning: Null value is eliminated by an aggregate or other SET operation in Aqua Data Studio
... solve this problem?. How to change the null data to 0 when no data in the table?.
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