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IN vs OR in the SQL WHERE Clause
...tion Plan.
I tried it with Oracle, and it was exactly the same.
CREATE TABLE performance_test AS ( SELECT * FROM dba_objects );
SELECT * FROM performance_test
WHERE object_name IN ('DBMS_STANDARD', 'DBMS_REGISTRY', 'DBMS_LOB' );
Even though the query uses IN, the Execution Plan says that it u...
Generating a unique machine id
...fo from Windows you could use EnumSystemFirmwareEntries, EnumSystemFirmwareTables and GetSystemFirmwareTable.
IIRC, the "unique id" from the CPUID instruction is deprecated from P3 and newer.
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Why use symbols as hash keys in Ruby?
...lso saves memory, because they are only stored once.
Ruby Symbols are immutable (can't be changed), which makes looking something up much easier
Short(ish) answer:
Using symbols not only saves time when doing comparisons, but also saves memory, because they are only stored once.
Symbols in Ruby ...
How to exit if a command failed?
...
set -e is not at all reliable, consistent or predictable! To convince yourself of that, review the exercises section of BashFAQ #105, or the table comparing different shells' behaviors at in-ulm.de/~mascheck/various/set-e
– Charles Duffy
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How do I check to see if a value is an integer in MySQL?
... matching the string to a regular expression. Simply do
select field from table where field REGEXP '^-?[0-9]+$';
this is reasonably fast. If your field is numeric, just test for
ceil(field) = field
instead.
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How can I escape a double quote inside double quotes?
..." sometimes
In your example, I would do it something like this:
$ dbtable=example
$ dbload='load data local infile "'"'gfpoint.csv'"'" into '"table $dbtable FIELDS TERMINATED BY ',' ENCLOSED BY '"'"'"' LINES "'TERMINATED BY "'"'\n'"'" IGNORE 1 LINES'
$ echo $dbload
which produces the follow...
How do I use regex in a SQLite query?
...ou need to invoke it slightly differently though, like this: SELECT * FROM table WHERE column regexp("myregexp")
– Tristan
May 30 '14 at 17:16
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Android: How to stretch an image to the screen width while maintaining aspect ratio?
...ing how simply, in Android, you can do "totally dynamic cell heights" in a table view .. err, I mean ListView. Enjoy.
<com.parse.ParseImageView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/post_image"
android:src="@drawable/icon_192"
...
How do I specify a password to 'psql' non-interactively?
...)" --rm postgres psql -h www.example.com dbname username -c 'SELECT * FROM table;'
– Bilal Akil
Nov 23 '17 at 4:34
3
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Places where JavaBeans are used?
...an use it to create a list of users wherein you store the data of the user table in the database:
List<User> users = new ArrayList<User>();
while (resultSet.next()) {
User user = new User();
user.setId(resultSet.getLong("id"));
user.setName(resultSet.getString("name"));
u...