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Avinash is sharing some cool facts about SQLite.

• SQLite is the most deployed and most used database. There are over one trillion (1000000000000 or a million million) SQLite databases in active use.

• SQLite is likely used more than all other database engines combined. Billions and billions of copies of SQLite exist in the wild. It’s everywhere.

These are mind blowing, have a look into that.

Article link

To extract the value of a tag from the given XML-like string in PL/SQL, you can use the EXTRACTVALUE function or XMLTABLE for XML processing.

Example Using EXTRACTVALUE

DECLARE
    xml_data CLOB := '<Status>200</Status><Message>Success</Message>';
    l_message VARCHAR2(50);
BEGIN
    -- Extract the FunctionalReferenceID value
    l_message := EXTRACTVALUE(XMLTYPE('<root>' || xml_data || '</root>'), '/root/Message');
    
    -- Print the value
    DBMS_OUTPUT.PUT_LINE('FunctionalReferenceID: ' || l_message);
END;

Example Using XMLTABLE

DECLARE
    xml_data CLOB := '<Status>200</Status><Message>Success</Message>';
    l_message VARCHAR2(50);
BEGIN
    -- Use XMLTABLE to extract the Message
    SELECT value
    INTO l_message
    FROM XMLTABLE(
        '/root/Message'
        PASSING XMLTYPE('<root>' || xml_data || '</root>')
        COLUMNS value VARCHAR2(50) PATH '.'
    );

    -- Print the value
    DBMS_OUTPUT.PUT_LINE('Message: ' || l_message);
END;

EXTRACTVALUE, XMLTABLE

For NVARCHAR2 and VARCHAR2 maximum size is 4000 bytes, or 32767 bytes if the MAX_STRING_SIZE initialization parameter is set to EXTENDED. This is useful you have to allocate more data to a variable.

You can run the below command to view the parameter.

show parameter MAX_STRING_SIZE;

References

Oracle Doc, Max string size

In Oracle PL/SQL, you can use the following commands to view table details:

1. DESCRIBE or DESC

   DESC table_name;
   

   Displays columns, data types, and constraints.

2. USER_TAB_COLUMNS

   SELECT COLUMN_NAME, DATA_TYPE, DATA_LENGTH
   FROM USER_TAB_COLUMNS
   WHERE TABLE_NAME = 'TABLE_NAME';
   

   Shows details about columns for tables owned by the user.

3. ALL_TAB_COLUMNS

   SELECT COLUMN_NAME, DATA_TYPE, DATA_LENGTH
   FROM ALL_TAB_COLUMNS
   WHERE TABLE_NAME = 'TABLE_NAME';
   

   Provides column information for tables accessible to the user.

4. DBMS_METADATA.GET_DDL

   SELECT DBMS_METADATA.GET_DDL('TABLE', 'TABLE_NAME') FROM DUAL;
   

   Displays the CREATE TABLE statement for table structure details.

To view constraints on the table, you can check here.

If your Oracle database has Flashback enabled, you can query past versions of data within a specified retention period. Here’s how to use Flashback to retrieve a prior state of data:

SELECT * 
FROM your_table AS OF TIMESTAMP (SYSTIMESTAMP - INTERVAL '5' MINUTE) 
WHERE your_condition;

Replace SYSTIMESTAMP - INTERVAL '5' MINUTE with the timestamp or interval that reflects when the data was last known to be in its old state.

Note: Flashback must be enabled, and it’s only available within the Flashback retention window, which depends on your database configuration.

References

Killians Bytes