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Transaction isolation levels relation with locks on table
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I want to understand the lock each transaction isolation takes on the table
For example, you have 3 concurrent processes A, B and C. A starts a transaction, writes data and commit/rollback (depending on results). B just executes a SELECT statement to read data. C reads and updates data. All t...
“Insert if not exists” statement in SQLite
...te database. I am trying to insert values ( users_id , lessoninfo_id ) in table bookmarks , only if both do not exist before in a row.
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“INSERT IGNORE” vs “INSERT … ON DUPLICATE KEY UPDATE”
...into a column with a NOT NULL constraint.
Inserting a row to a partitioned table, but the values you insert don't map to a partition.
If you use REPLACE, MySQL actually does a DELETE followed by an INSERT internally, which has some unexpected side effects:
A new auto-increment ID is allocated....
Safely remove migration In Laravel
...p-autoload
Modify your database: Remove the last entry from the migrations table
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MySQL root password change
... to reset my MySQL root password. I have run the mysqld_safe --skip-grant-tables, updated the root password, and checked the user table to make sure it is there. Once restarting the mysql daemon I tried logging in with the new root password that I just set and still get Access denied for user 'roo...
How to do a FULL OUTER JOIN in MySQL?
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For a code SAMPLE transcribed from this SO question you have:
with two tables t1, t2:
SELECT * FROM t1
LEFT JOIN t2 ON t1.id = t2.id
UNION
SELECT * FROM t1
RIGHT JOIN t2 ON t1.id = t2.id
The query above works for special cases where a FULL OUTER JOIN operation would not produce any duplicat...
Setting table row height
...nly does now. anyway this is the solution I found to be best since the way table cells work is to expand to their content. so height in a td is effectively min-height, which in this case is actually what you want
– Simon_Weaver
Aug 3 '14 at 23:21
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How to select from subquery using Laravel Query Builder?
...Abc::where(..)->groupBy(..); // Eloquent Builder instance
$count = DB::table( DB::raw("({$sub->toSql()}) as sub") )
->mergeBindings($sub->getQuery()) // you need to get underlying Query Builder
->count();
Mind that you need to merge bindings in correct order. If you have ot...
Get button click inside UITableViewCell
I have a view controller with a table view and a separate nib for the table cell template. The cell template has some buttons. I want to access the button click along with the index of the cell clicked inside the view controller where I have defined the Table view.
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Best way to strip punctuation from a string
...g.punctuation))
It's performing raw string operations in C with a lookup table - there's not much that will beat that but writing your own C code.
If speed isn't a worry, another option though is:
exclude = set(string.punctuation)
s = ''.join(ch for ch in s if ch not in exclude)
This is faster...