大约有 40,000 项符合查询结果（耗时：0.0236秒） [XML]
How do you convert a DataTable into a generic list?
...ataTable
//using lamdaexpression
emp = (from DataRow row in dt.Rows
select new Employee
{
_FirstName = row["FirstName"].ToString(),
_LastName = row["Last_Name"].ToString()
}).ToList();
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How do I see all foreign keys to a table or column?
...
For a Table:
SELECT
TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME, REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME
FROM
INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE
REFERENCED_TABLE_SCHEMA = '<database>' AND
REFERENCED_TABLE_NAME = '<...
python-pandas and databases like mysql
...a_conn = cx_Oracle.connect('your_connection_string')
df_ora = pd.read_sql('select * from user_objects', con=ora_conn)
print 'loaded dataframe from Oracle. # Records: ', len(df_ora)
ora_conn.close()
And here is the equivalent example for MySQLdb:
import MySQLdb
mysql_cn= MySQLdb.connect(host='...
SQL SELECT speed int vs varchar
...k: A=261MB B=292MB C=322MB
Non-indexed by id: select count(*), select by id: 450ms same on all tables
Insert* one row per TX: B=9ms/record C=9ms/record
Bulk insert* in single TX: B=140usec/record C=180usec/record
Indexed by id, select by id: B=about 2...
Query to list all stored procedures
...e not in the master database, system stored procedures won't be returned.
SELECT *
FROM DatabaseName.INFORMATION_SCHEMA.ROUTINES
WHERE ROUTINE_TYPE = 'PROCEDURE'
If for some reason you had non-system stored procedures in the master database, you could use the query (this will filter out MOST ...
How do I check if a SQL Server text column is empty?
...
Actually, you just have to use the LIKE operator.
SELECT * FROM mytable WHERE mytextfield LIKE ''
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Write a number with two decimal places SQL server
...
try this
SELECT CONVERT(DECIMAL(10,2),YOURCOLUMN)
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How to select a CRAN mirror in R
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Repository selection screen cannot be shown on your system (OS X), since OS X no longer includes X11. R tries to show you the prompt through X11. Install X11 from http://xquartz.macosforge.org/landing/. Then run the install command. The...
Why shouldn't I use mysql_* functions in PHP?
... 5.5 and above)
$link = mysql_connect('localhost', 'user', 'pass');
mysql_select_db('testdb', $link);
mysql_set_charset('UTF-8', $link);
With PDO: All you need to do is create a new PDO object. The constructor accepts parameters for specifying the database source PDO's constructor mostly takes fo...
Need to list all triggers in SQL Server database with table name and table's schema
...
Here's one way:
SELECT
sysobjects.name AS trigger_name
,USER_NAME(sysobjects.uid) AS trigger_owner
,s.name AS table_schema
,OBJECT_NAME(parent_obj) AS table_name
,OBJECTPROPERTY( id, 'ExecIsUpdateTrigger') AS isupda...