How to express not equal to empty in Oracle

The syntax in Oracle to express not equal to null is IS NOT NULL. This operator checks whether a column or variable contains data; values ​​that contain no data or contain an empty string are treated as NULL. Use the IS NOT NULL operator to filter the result set or to ensure that a column or variable is not NULL before inserting or updating.

The syntax for expressing not equal to null in Oracle

Question:How to express in Oracle Does it mean it is not equal to empty?

Answer:

The syntax in Oracle to express not equal to null is IS NOT NULL.

Detailed description:

IS NOT NULL operator is used to check whether a column or variable is not equal to a null value. When a column or variable contains no data or contains an empty string, it is treated as a NULL value.

You can use the IS NOT NULL operator to filter the result set or to ensure that a column or variable is not NULL before inserting or updating.

Example:

<code class="sql">-- 选择不等于空值的 "name" 列
SELECT "name"
FROM "table_name"
WHERE "name" IS NOT NULL;

-- 确保在插入之前 "email" 列不为空
INSERT INTO "table_name" ("email")
VALUES ('john@example.com')
WHERE "email" IS NOT NULL;</code>

Note:

• IS NOT NULL Operator Unlike the NOT NULL constraint. The NOT NULL constraint enforces that the column is always not NULL, while the IS NOT NULL operator only checks if the current value is not NULL.
• IS NOT NULL operator can improve query performance when used in a WHERE clause because Oracle can skip checking for null values.

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