What symbols are used to connect strings to the database in Oracle?

Oracle uses the "||" symbol to connect strings. The usage method is as follows: connect the strings to be connected with the "||" symbol; the priority of string connection is low, and parentheses need to be used to ensure the priority; an empty string will still be an empty string after connection; NULL value connection is still NULL.

Oracle string connection symbols:

In Oracle, strings can use "||" Symbolic link.

String concatenation method

To concatenate two strings, use the "||" notation to put them together as shown below:

SELECT 'Hello' || 'World'; -- 输出 'HelloWorld'

Examples

Let's see some examples to understand the usage of string concatenation:

SELECT 'First Name: ' || first_name FROM employee;
-- 将字符串 'First Name: ' 与 employee 表中的 first_name 字段连接

SELECT last_name || ', ' || first_name FROM employee;
-- 连接 last_name、', ' 和 first_name 字段，以逗号分隔

SELECT 'Total Sales: $' || TO_CHAR(sales_amount, '999,999.99');
-- 将字符串 'Total Sales: $' 与 sales_amount 字段连接，并将其格式化为货币值

Note

• String concatenation symbols"||" has lower precedence, so parentheses are needed before other operators to enforce precedence.
• Oracle does not automatically remove empty strings when connecting. If you concatenate two empty strings, the result will still be an empty string.
• If both concatenated strings are NULL, the result will also be NULL.

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