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PHP + MySQL transactions examples
...b_passwd,$db_name); // error-check this
// note: this is meant for InnoDB tables. won't work with MyISAM tables.
try {
$conn->autocommit(FALSE); // i.e., start transaction
// assume that the TABLE groups has an auto_increment id field
$query = "INSERT INTO groups (name) ";
$qu...
map vs. hash_map in C++
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hash_map (unordered_map in TR1 and Boost; use those instead) use a hash table where the key is hashed to a slot in the table and the value is stored in a list tied to that key.
map is implemented as a balanced binary search tree (usually a red/black tree).
An unordered_map should give slightly ...
CodeIgniter activerecord, retrieve last insert id?
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for Specific table you cannot use $this->db->insert_id() . even the last insert happened long ago it can be fetched like this. may be wrong. but working well for me
$this->db->select_max('{primary key}');
$result= $...
How to change column datatype from character to numeric in PostgreSQL 8.4
...rom old to new type.
So this might work (depending on your data):
alter table presales alter column code type numeric(10,0) using code::numeric;
-- Or if you prefer standard casting...
alter table presales alter column code type numeric(10,0) using cast(code as numeric);
This will fail if you h...
Count the number of occurrences of a string in a VARCHAR field?
I have a table like this:
7 Answers
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Most efficient way to remove special characters from string
...ms.
The price to pay is, of course, the initialization of the huge lookup table and keeping it in memory. Well, it's not that much data, but it's much for such a trivial function...
private static bool[] _lookup;
static Program() {
_lookup = new bool[65536];
for (char c = '0'; c <= '9'; ...
python-pandas and databases like mysql
...pass@host:port/schema', echo=False)
f = pd.read_sql_query('SELECT * FROM mytable', engine, index_col = 'ID')
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What is the MySQL VARCHAR max size?
...QL has a maximum row size limit
The internal representation of a MySQL table has a maximum row size limit of 65,535 bytes, not counting BLOB and TEXT types. BLOB and TEXT columns only contribute 9 to 12 bytes toward the row size limit because their contents are stored separately from the rest of...
Django: How to completely uninstall a Django app?
...dy management command that will give you the necessary SQL to drop all the tables for an app. See the sqlclear docs for more information. Basically, running ./manage.py sqlclear my_app_name gets you get the SQL statements that should be executed to get rid of all traces of the app in your DB. You st...
Vertical (rotated) text in HTML table
Is there a (portable) way to rotate text in a HTML table cell by 90°?
11 Answers
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