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

Breaking columns to a new line in flexbox requires a small hack: add an element with width: 100% wherever you want to wrap your columns to a new line.

<div class="container text-center">
  <div class="row">
    <div class="col-6 col-sm-3">.col-6 .col-sm-3</div>
    <div class="col-6 col-sm-3">.col-6 .col-sm-3</div>

    <!-- Force next columns to break to new line -->
    <div class="w-100"></div>

    <div class="col-6 col-sm-3">.col-6 .col-sm-3</div>
    <div class="col-6 col-sm-3">.col-6 .col-sm-3</div>
  </div>
</div>

You can also apply this break at specific breakpoints with our responsive display utilities.

<div class="container text-center">
  <div class="row">
    <div class="col-6 col-sm-4">.col-6 .col-sm-4</div>
    <div class="col-6 col-sm-4">.col-6 .col-sm-4</div>

    <!-- Force next columns to break to new line at md breakpoint and up -->
    <div class="w-100 d-none d-md-block"></div>

    <div class="col-6 col-sm-4">.col-6 .col-sm-4</div>
    <div class="col-6 col-sm-4">.col-6 .col-sm-4</div>
  </div>
</div>

References

Bootstrap Doc

To update a column with a random value in PL/SQL, you can use the DBMS_RANDOM package, which provides functions for generating random numbers or strings.

To update random number

BEGIN
    UPDATE employees
    SET salary = ROUND(DBMS_RANDOM.VALUE(100, 500));
    COMMIT;
END;

• DBMS_RANDOM.VALUE(100, 500) generates a random decimal number between 100 and 500.
• ROUND is used to convert the decimal value to an integer.

To update random string

BEGIN
   UPDATE employees
    SET password = DBMS_RANDOM.STRING('x', 8);  -- 'x' specifies alphanumeric characters
    COMMIT;
END;

• DBMS_RANDOM.STRING('x', 8) generates an 8-character alphanumeric string.
• ‘x’ specifies alphanumeric characters (letters and numbers). Other options include ‘a’ for alphabets and ‘u’ for uppercase only.