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How to declare a type as nullable in TypeScript?
...wever, salary = undefined; will work just fine in this case. Solution: use Union i.e. '|'
– Ankur Nigam
Apr 21 at 6:19
...
Real life example, when to use OUTER / CROSS APPLY in SQL
...1) Top N per group queries (can be more efficient for some cardinalities)
SELECT pr.name,
pa.name
FROM sys.procedures pr
OUTER APPLY (SELECT TOP 2 *
FROM sys.parameters pa
WHERE pa.object_id = pr.object_id
ORDER BY pr.n...
MySQL: Insert record if not exists in table
...oDB;
Insert a record:
INSERT INTO table_listnames (name, address, tele)
SELECT * FROM (SELECT 'Rupert', 'Somewhere', '022') AS tmp
WHERE NOT EXISTS (
SELECT name FROM table_listnames WHERE name = 'Rupert'
) LIMIT 1;
Query OK, 1 row affected (0.00 sec)
Records: 1 Duplicates: 0 Warnings: 0
...
How can mixed data types (int, float, char, etc) be stored in an array?
...
You can make the array elements a discriminated union, aka tagged union.
struct {
enum { is_int, is_float, is_char } type;
union {
int ival;
float fval;
char cval;
} val;
} my_array[10];
The type member is used to hold the choice of w...
Creating a config file in PHP
...s is best considered where you have a huge amount of configuration but are selective in what is needed for the current task - I was surprised to find that at around 150 data items, it was quicker to retrieve the data from a local MySQL instance than to unserialize a datafile.
OTOH its not a good pl...
Can't connect to local MySQL server through socket '/tmp/mysql.sock
When I attempted to connect to a local MySQL server during my test suite, it
fails with the error:
32 Answers
...
Downloading MySQL dump from command line
...tion to a more noob-friendly service, I need to download the contents of a MySQL database. Is there a way I can do this from the command line?
...
How to select date from datetime column?
...ry.
Use BETWEEN or >, <, = operators which allow to use an index:
SELECT * FROM data
WHERE datetime BETWEEN '2009-10-20 00:00:00' AND '2009-10-20 23:59:59'
Update: the impact on using LIKE instead of operators in an indexed column is high. These are some test results on a table with 1,...
How to get ID of the last updated row in MySQL?
...)
SET @update_id := 0;
UPDATE some_table SET column_name = 'value', id = (SELECT @update_id := id)
WHERE some_other_column = 'blah' LIMIT 1;
SELECT @update_id;
EDIT by aefxx
This technique can be further expanded to retrieve the ID of every row affected by an update statement:
SET @uids := nul...
Why is '+' not understood by Python sets?
...ts don't have an implementation for the + operator.
You can use | for set union and & for set intersection.
Sets do implement - as set difference. You can also use ^ for symmetric set difference (i.e., it will return a new set with only the objects that appear in one set but do not appear in b...