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SQL Inner-join with 3 tables?
...
You can do the following (I guessed on table fields,etc)
SELECT s.studentname
, s.studentid
, s.studentdesc
, h.hallname
FROM students s
INNER JOIN hallprefs hp
on s.studentid = hp.studentid
INNER JOIN halls h
on hp.hallid = h.hallid
Based on your request for ...
How to test an SQL Update statement before running it?
...yway) you can also do a sanity check which rows are affected by running a select using the same WHERE clause as the UPDATE.
So if you UPDATE is
UPDATE foo
SET bar = 42
WHERE col1 = 1
AND col2 = 'foobar';
The following will show you which rows will be updated:
SELECT *
FROM foo
WHERE col1 ...
How to get first character of a string in SQL?
...
SELECT SUBSTR(thatColumn, 1, 1) As NewColumn from student
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How to get the selected radio button’s value?
...r working. I just want to find the value of the radio button (which one is selected) and return it to a variable. For some reason it keeps returning undefined .
...
Restful way for deleting a bunch of items
...away with the javascript confirm on the same page, and instead, create the selection and redirect to it, showing a confirm message on that page. In other words:
From:
http://example.com/resources/
do a
POST with a selection of the ID's to:
http://example.com/resources/selections
which, if succes...
How can I get column names from a table in SQL Server?
... much more by querying the Information Schema views.
This sample query:
SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = N'Customers'
Can be made over all these DB objects:
CHECK_CONSTRAINTS
COLUMN_DOMAIN_USAGE
COLUMN_PRIVILEGES
COLUMNS
CONSTRAINT_COLUMN_USAGE
CONSTRAINT_...
How to find all duplicate from a List? [duplicate]
...d then filter out any of the enumerables that have a Count of <=1, then select their keys to get back down to a single enumerable:
var duplicateKeys = list.GroupBy(x => x)
.Where(group => group.Count() > 1)
.Select(group => group.Key);
...
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 = '<...
Best way to work with dates in Android SQLite [closed]
...ing (that is newest date goes first):
public static final String QUERY = "SELECT table._id, table.dateCol FROM table ORDER BY table.dateCol DESC";
//...
Cursor cursor = rawQuery(QUERY, null);
cursor.moveToFirst();
while (!cursor.isAfterLast()) {
// Process results
}
Al...
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='...