How to query data of all fields in oracle

How to query all fields in oracle: 1. Use the "SELECT all field name list FROM data table name;" statement. Use English commas "," to separate multiple field names; 2. Use "SELECT * FROM Data table name;" statement.

The operating environment of this tutorial: Windows 7 system, Oracle 11g version, Dell G3 computer.

In Oracle, a table is composed of columns and rows. Data can be queried using the SELECT statement. Querying data refers to using different query methods to obtain different data from the database according to needs. It is the most frequently used and important operation.

To retrieve data from one or more columns (column_1, column_2,...,column_n) of a table, use a SELECT statement with the following syntax:

SELECT
  column_1, 
  column_2, 
  ...
FROM
  table_name;

In this SELECT statement :

• First, you need to specify the name of the table where the data is to be queried.

• Secondly, specify the columns in which you want to return data. If you need to return multiple columns, you need to separate these columns with commas (,).

oracle queries the data of all fields

Querying all fields refers to querying the data of all fields in the table. There are the following 2 ways to query all fields in the table.

• Use the "*" wildcard to query all fields

• List all fields of the table

Example:

For example, the customers table in the sample database has the following columns: customer_id, name, address, website and credit_limit. customersThere is also corresponding data in these columns in the table.

The following example will retrieve data in all columns of the customers table and list the names of all columns, as shown below:

SELECT
    customer_id,
    name,
    address,
    website,
    credit_limit
FROM
    customers;

Execute the above example code , the following results are obtained -

#For convenience, to view all columns, you can use the abbreviation asterisk (*) to instruct Oracle to return data for all columns from the table, as shown below :

SELECT
    *
FROM
    customers;

Execute the above example code and get the following results-

Please note that you can only use asterisks (*) test. In practice, even if you want to retrieve data from all columns of a table, you should explicitly specify the column from which you want to query the data.

This is because of business changes, the table may have more or fewer columns in the future. If you use asterisks (*) in your application code, it is assumed that the table has a fixed set of columns, but the application may not handle other unrelated columns or access deleted columns.

Recommended tutorial: "Oracle Tutorial"

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