SQL Oracle 空条件检查“ ”条件
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Oracle empty conditions to check the ' ' condition
提问by reg10
How do I compare a VARCHAR2variable, which is an empty value?
如何比较一个VARCHAR2变量，它是一个空值？
回答by Karel Petranek
Oracle doesn't differentiate between empty strings and NULL. To check if a variable is an empty string, use the IS NULLsyntax.
Oracle 不区分空字符串和 NULL。要检查变量是否为空字符串，请使用IS NULL语法。
回答by Ollie
You could use either of these:
您可以使用以下任一方法：
IF v_test IS NULL
THEN
-- Business Logic
or
或者
IF NVL(v_test, 'NULL') = 'NULL'
THEN
-- Business Logic
Your question does say "compare" a VARCHAR variable which is null so if you are comparing it to another variable then:
您的问题确实说“比较”一个为空的 VARCHAR 变量，因此如果您将它与另一个变量进行比较，则：
IF (v_test1 IS NULL and v_test2 IS NULL)
THEN
-- Business Logic
That would check if they are both null.
那将检查它们是否都为空。
Hope it helps...
希望能帮助到你...
