There are the following methods to obtain time in Oracle: CURRENT_TIMESTAMP: Returns the current system time, accurate to seconds. SYSTIMESTAMP: More accurate than CURRENT_TIMESTAMP, to nanoseconds. SYSDATE: Returns the current system date, excluding the time part. TO_CHAR(SYSDATE, 'YYY-MM-DD HH24:MI:SS'): Converts the current system date and time to a specific format. EXTRACT: Extracts a specific part from a time value, such as a year, month, or hour.
How to get time using Oracle
There are several ways to get time in Oracle, and the following are the most commonly used methods:
1. CURRENT_TIMESTAMP
The CURRENT_TIMESTAMP
function returns the current system time, accurate to seconds. It is usually used to insert records into a database to record when it was created or updated.
Example:
<code class="sql">SELECT CURRENT_TIMESTAMP FROM DUAL;</code>
2. SYSTIMESTAMP
SYSTIMESTAMP
function also returns the current system time, but it is more accurate than CURRENT_TIMESTAMP
, and is accurate to nanoseconds.
Example:
<code class="sql">SELECT SYSTIMESTAMP FROM DUAL;</code>
3. SYSDATE
The SYSDATE
function returns the current system date, excluding the time part.
Example:
<code class="sql">SELECT SYSDATE FROM DUAL;</code>
4. TO_CHAR(SYSDATE, 'YYY-MM-DD HH24:MI:SS')
This query converts the current system date and time to a specific format ( YYYY-MM-DD HH24:MI:SS
).
Example:
<code class="sql">SELECT TO_CHAR(SYSDATE, 'YYYY-MM-DD HH24:MI:SS') FROM DUAL;</code>
5. EXTRACT
The EXTRACT
function can be used to extract specific parts from time values, such as year, month, or hour.
Example:
<code class="sql">SELECT EXTRACT(YEAR FROM SYSDATE) FROM DUAL; -- 获取年份SELECT EXTRACT(MONTH FROM SYSDATE) FROM DUAL; -- 获取月份SELECT EXTRACT(HOUR FROM SYSDATE) FROM DUAL; -- 获取小时</code>
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