How to write SQL queries with double quotes in all column names without mentioning the column name in the table?

 Writing SQL queries with double quotes around all column names without specifying the column names in the table is not a common or recommended practice. However, in some database systems, you can achieve this by dynamically constructing SQL queries using system catalogs or metadata to obtain column names. Below are examples for PostgreSQL and Oracle databases, which support this kind of dynamic query construction:


**PostgreSQL:**


In PostgreSQL, you can use the `information_schema` to query the column names of a table and dynamically build your SQL query:


```sql

DO $$ 

DECLARE 

    col_name text;

    query text;

BEGIN

    FOR col_name IN 

        (SELECT column_name 

         FROM information_schema.columns 

         WHERE table_name = 'your_table_name') 

    LOOP

        query := query || '"' || col_name || '", ';

    END LOOP;

    

    query := 'SELECT ' || substring(query, 1, length(query) - 2) || ' FROM your_table_name';

    EXECUTE query;

END $$;

```


Replace `'your_table_name'` with the name of your table.


**Oracle:**


In Oracle, you can use a similar approach with the `USER_TAB_COLUMNS` system table to obtain column names:


```sql

DECLARE

    col_name VARCHAR2(100);

    query VARCHAR2(4000);

BEGIN

    FOR col_rec IN (SELECT column_name

                    FROM user_tab_columns

                    WHERE table_name = 'your_table_name') 

    LOOP

        col_name := col_rec.column_name;

        query := query || '"' || col_name || '", ';

    END LOOP;


    query := 'SELECT ' || SUBSTR(query, 1, LENGTH(query) - 2) || ' FROM your_table_name';

    EXECUTE IMMEDIATE query;

END;

```


Replace `'your_table_name'` with the name of your table.


Please note that constructing SQL queries in this way can introduce security risks (SQL injection) and may not be the best approach for most situations. It's important to validate and sanitize user input and consider other options, like using parameterized queries, to mitigate these risks.

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