***SUBSTR*** [(documentation)][1]:

    SELECT SUBSTR(OrderNo, 1, 2) As NewColumnName from shipment

When selected, it&#39;s like any other column. You should give it a name (with `As` keyword), and you can selected other columns in the same statement:


    SELECT SUBSTR(OrderNo, 1, 2) As NewColumnName, column2, ... from shipment


  [1]: http://download.oracle.com/docs/cd/B28359_01/olap.111/b28126/dml_functions_2101.htm

    select substr(orderno,1,2) from shipment;

You may want to have a look at the [documentation][1] too.


  [1]: https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/SUBSTR.html#GUID-C8A20B57-C647-4649-A379-8651AA97187E

take a look [here][1]

    SELECT SUBSTR(&#39;Take the first four characters&#39;, 1, 4) FIRST_FOUR FROM DUAL;

[1]:http://psoug.org/reference/substr_instr.html

Easy:

    SELECT SUBSTR(OrderNo, 1, 2) FROM shipment;

Just use [SUBSTR][1] function. It takes 3 parameters: String column name, starting index and length of substring:

    select SUBSTR(OrderNo, 1, 2) FROM shipment;


  [1]: http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/functions162.htm

Try select substr(orderno, 1,2) from shipment;

The Security services API doesn&#39;t appear to allow me to compute a hash directly. There are plenty of public domain and liberally licensed versions available, but I&#39;d rather use a system library implementation if possible.

The data is accessible via NSData, or plain pointers.

The cryptographic strength of the hash is important to me. SHA-256 is the minimum acceptable hash size.

How can I compute a SHA-2 (ideally SHA 256 or SHA 512) hash in iOS?

I created a bare repository on a file-server in my local network at home.
After this i pushed a branch of an existing repository from my desktop-pc to this new remote repository.

Pushing worked perfectly and it seems, that all data arrived (a &quot;git branch -va&quot; gives me the correct data). 
But i cannot use git log or git show on the bare repository.
i get an:

`fatal: bad default revision &#39;HEAD&#39;`

or simply no output

is this normal for bare repositories? Is there another possibility to visualize everything?


Edit:
The fatal error is solved now, but i receive no output from &quot;git log&quot; or &quot;git log unstable&quot;. Same command on the desktop-pc works perfectly


git log and show on a bare repo

Suppose I have a column name `OrderNo` with value `AO025631` in a table `shipment`.

I am trying to query the table so that I can get only first two character of column value i.e. `AO`.

Can I do this in the SQL query itself?   


How to get first two characters of a string in oracle query?

Suppose I have a column name <code>OrderNo</code> with value <code>AO025631</code> in a table <code>shipment</code>.
I am trying to query the table so that I can get only first two character of column value i.e. <code>AO</code>.
Can I do this in the SQL query itself?

For example, I want to do the following on a database update.

Is there a constant I can use instead of `null`, which won&#39;t compile if I use it like:

&lt;!-- language-all: lang-java --&gt;

    ContentValues args = new ContentValues();
    args.put(KEY_RISK_AMOUNT, null); // what constant do I use instead of null?



How do I update an android sqlite database column value to null using ContentValues?

Using postgres 8.4,  My goal is to update existing table:

    CREATE TABLE public.dummy
    (
      address_id SERIAL,
      addr1 character(40),
      addr2 character(40),
      city character(25),
      state character(2),
      zip character(5),
      customer boolean,
      supplier boolean,
      partner boolean
      
    )
    WITH (
      OIDS=FALSE
    );

Initially i tested my query using insert statement:

    insert into address customer,supplier,partner
    SELECT  
    	case when cust.addr1 is not null then TRUE else FALSE end customer, 
    	case when suppl.addr1 is not null then TRUE else FALSE end supplier,
    	case when partn.addr1 is not null then TRUE else FALSE end partner
    from (
    	SELECT *
    		from address) pa
    	left outer join cust_original cust
    		on (pa.addr1=cust.addr1 and pa.addr2=cust.addr2 and pa.city=cust.city 
    			and pa.state=cust.state and substring(cust.zip,1,5) = pa.zip  )
    	left outer join supp_original suppl 
    		on (pa.addr1=suppl.addr1 and pa.addr2=suppl.addr2 and pa.city=suppl.city 
    			    and pa.state=suppl.state and pa.zip = substring(suppl.zip,1,5))
    	left outer join partner_original partn
    		on (pa.addr1=partn.addr1 and pa.addr2=partn.addr2 and pa.city=partn.city
    			      and pa.state=partn.state and pa.zip = substring(partn.zip,1,5) )
    where pa.address_id = address_id

being Newbie I&#39;m failing converting to update statement ie., updating existing rows with values returned by select statement.
Any help is highly appreciated.

updating table rows in postgres using subquery

I have very simple question but i did&#39;t get any simple code to exit from SP using Mysql.
Can anyone share with me how to do that?

    CREATE PROCEDURE SP_Reporting(IN tablename VARCHAR(20))
    BEGIN
         IF tablename IS NULL THEN
              #Exit this stored procedure here
         END IF;
    
         #proceed the code
    END;

Mysql - How to quit/exit from stored procedure

I&#39;m using Postgres and cannot manage to get the last record of my table:

     my_query = client.query(&quot;SELECT timestamp,value,card from my_table&quot;);

How can I do that knowning that timestamp is a unique identifier of the record ?

Get last record of a table in Postgres

Is there any possibility to use an &quot;after update&quot; trigger only in the case the data has been REALLY changed.
I know of &quot;NEW and OLD&quot;. But when using them I&#39;m only able to compare columns.
For example &quot;NEW.count &lt;&gt; OLD.count&quot;.

But I want something like: run trigger if &quot;NEW &lt;&gt; OLD&quot;

An Example:

    create table foo (a INT, b INT);
    create table bar (a INT, b INT);

    INSERT INTO foo VALUES(1,1);
    INSERT INTO foo VALUES(2,2);
    INSERT INTO foo VALUES(3,3);

    CREATE TRIGGER ins_sum
        AFTER UPDATE ON foo
        FOR EACH ROW
        INSERT INTO bar VALUES(NEW.a, NEW.b);

    UPDATE foo SET b = 3 WHERE a=3;
    Query OK, 0 rows affected (0.00 sec)
    Rows matched: 1  Changed: 0  Warnings: 0


    select * from bar;
    +------+------+
    | a    | b    |
    +------+------+
    |    3 |    3 |
    +------+------+

The point is, there was an update, but **nothing has changed**.
But the trigger ran anyway. IMHO there should be a way it doesn&#39;t.

I know that I could have used 

&gt; IF NOW.b &lt;&gt; OLD.b

for this example.

BUT imagine a large table with changing columns.
You have to compare every column and if the database changes you have to adjust the trigger.
AND it doesn&#39;t &quot;feel&quot; good to compare every column of the row hardcoded :)

**Addition**

As you can see on the line 

&gt; Rows matched: 1  Changed: 0  Warnings: 0

MySQL knows that the line didn&#39;t change. But it doesn&#39;t share this knowledge with the trigger.
A trigger like &quot;AFTER REAL UPDATE&quot; or something like this would be cool.


MySQL Trigger after update only if row has changed

I want to check SID and current database name.

I am using following query for checking oracle SID

    select instance from v$thread;

but table or view does not exist error is coming.

I am using following query for checking current database name

    select name from v$database;

but table or view does not exist error is coming.

Any idea for above two problems?






Checking oracle sid and database name

If you execute this query

    SELECT &#39;test-a1&#39; AS name1, &#39;test-a2&#39; AS name2
the result will be a one row-selection with two columns having these values: 

    test-a1, test-a2

How can I modify the above query to have a selection with several rows, e.g.

    test-a1, test-a2
    test-b1, test-b2
    test-c1, test-c2

I know how to do this with UNION but I feel that there exists a more simple way to do it.

PS. Sorry for such a basic question, it is very hard to google it.

How to select several hardcoded SQL rows?

How do I add a simple check before adding a column to a table for an oracle db? I&#39;ve included the SQL that I&#39;m using to add the column.

    ALTER TABLE db.tablename 
      ADD columnname NVARCHAR2(30);



How to check if a column exists before adding it to an existing table in PL/SQL?

How would I go about creating a database from a dump file? I do not have an existing database with the same structure on my system so it has to be complete with jobs, events, tables, and so on. 

I placed the dump and log file in E: drive

I have tried the import utility 

    E:/&gt;impdp system/tiger@oratest FILE=WB_PROD_FULL_20MAY11.dmp

But I&#39;m getting error as

    invalid argument value
    bad dump file specification
    unable to open dump file &quot;E:\app\admin\oratest\dpdump\WB_PROD_F
    ULL_20MAY11.dmp&quot; for read
    unable to open file
    unable to open file
    (OS 2) The system cannot find the file specified.

And when I see in Windows Explorer DMP file(taken from Linux server) is showing as Crash dump file

I don&#39;t understand how I can resolve this issue. Please help me to solve this issue.

I&#39;m a complete newbie on Oracle... 




How to import an Oracle database from dmp file and log file?

I am getting the above error when trying to connect to a server database from a client using service name `orcl`. It is getting connected when I am using the other service name i.e. `dms`

Below is my `listener.ora`

    SID_LIST_LISTENER =
      (SID_LIST =
        (SID_DESC =
          (SID_NAME = dms)
          (SERVICE_NAME = dms)
          (ORACLE_HOME = /home/oracle/app/oracle/product/11.2.0/dbhome_1)
    #      (PROGRAM = extproc)
        )
      (SID_DESC =
         (SID_NAME = orcl)
         (SERVICE_NAME = dms)
        # (GLOBAL_DBANME = orcl)
          (ORACLE_HOME = /home/oracle/app/oracle/product/11.2.0/dbhome_1)
       #  (PROGRAM = extproc)
      )
      )
    
    
    LISTENER =
      (DESCRIPTION_LIST =
        (DESCRIPTION =
          (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
          (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.53)(PORT = 1521))
    
        )
      )
    
    ADR_BASE_LISTENER = /home/oracle/app/oracle
    and tnsnames.ora
    ORCL =
      (DESCRIPTION =
        (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.53)(PORT = 1521))
        (CONNECT_DATA =
          (SERVER = DEDICATED)
         #(SERVICE_NAME = orcl.localdomain)
          (ORACLE_SID = dms)
          (SERVICE_NAME = orcl)
        )
      )
    
    DMS =
      (DESCRIPTION =
        (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.53)(PORT = 1521))
        (CONNECT_DATA =
          (SERVER = DEDICATED)
          (SERVICE_NAME = dms)
          (ORACLE_SID = dms)
        )
      )

Please tell me what to do?

Content Type	Original Author	Original Content on Stackoverflow
Question	Vivek	View Question on Stackoverflow
Solution 1 - Sql	manji	View Answer on Stackoverflow
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Solution 6 - Sql	Shepherdess	View Answer on Stackoverflow

How to get first two characters of a string in oracle query?

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git log and show on a bare repo

How can I compute a SHA-2 (ideally SHA 256 or SHA 512) hash in iOS?

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