大约有 40,000 项符合查询结果（耗时：0.0489秒） [XML]
Insert into a MySQL table or update if exists
I want to add a row to a database table, but if a row exists with the same unique key I want to update the row.
11 Answers
...
What exactly are DLL files, and how do they work?
...Dynamic Link Libraries (DLL)s are like EXEs but they are not directly executable. They are similar to .so files in Linux/Unix. That is to say, DLLs are MS's implementation of shared libraries.
DLLs are so much like an EXE that the file format itself is the same. Both EXE and DLLs are based on ...
How can I easily view the contents of a datatable or dataview in the immediate window
...ll be at a breakpoint in my code and I want to view the contents of a DataTable variable (or a DataTable in a DataSet ). The quick watch doesn't give you a very clear view of the contents. How can I view them easily?
...
postgresql COUNT(DISTINCT …) very slow
...
You can use this:
SELECT COUNT(*) FROM (SELECT DISTINCT column_name FROM table_name) AS temp;
This is much faster than:
COUNT(DISTINCT column_name)
share
|
improve this answer
|
...
PreparedStatement IN clause alternatives?
...lable here.
The suggested options are:
Prepare SELECT my_column FROM my_table WHERE search_column = ?, execute it for each value and UNION the results client-side. Requires only one prepared statement. Slow and painful.
Prepare SELECT my_column FROM my_table WHERE search_column IN (?,?,?) and exe...
List of all index & index columns in SQL Server DB
...This query's getting pretty close to what you're looking for:
SELECT
TableName = t.name,
IndexName = ind.name,
IndexId = ind.index_id,
ColumnId = ic.index_column_id,
ColumnName = col.name,
ind.*,
ic.*,
col.*
FROM
sys.indexes ind
INNER JOIN
sys.i...
In C/C++ what's the simplest way to reverse the order of bits in a byte?
...
If you are talking about a single byte, a table-lookup is probably the best bet, unless for some reason you don't have 256 bytes available.
share
|
improve this answ...
How can I join multiple SQL tables using the IDs?
I have 4 different tables that I want to join. The tables are structured with columns as follows:
4 Answers
...
MySQL dump by query
...
not mysqldump, but mysql cli...
mysql -e "select * from myTable" -u myuser -pxxxxxxxxx mydatabase
you can redirect it out to a file if you want :
mysql -e "select * from myTable" -u myuser -pxxxxxxxx mydatabase > mydumpfile.txt
Update:
Original post asked if he could dump f...
Generating an Excel file in ASP.NET [closed]
... Excel features
Do not require an install copy of Excel
Can generate Pivot tables
Can be generated using open source project EPPlus
Cons:
Limited compatibility outside Excel 2007 (shouldn't be a problem nowadays)
Complicated unless you're using a third party component
SpreadSheetML (open form...