如何在 Flink SQL 中将 TZ 日期时间转换为时间戳（3）

Question

How do you convert a DateTime with the TZ to Timestamp(3) in Flink SQL v1.13?

TO_TIMESTAMP('2021-12-16T20:29:37Z', 'yyyy-MM-dd HH:mm:ss') //returns NULL

TO_TIMESTAMP('2021-12-16 20:29:37', 'yyyy-MM-dd HH:mm:ss') //returns 2021-12-16T20:29:37

TO_TIMESTAMP('2021-12-16T20:29:37', 'yyyy-MM-dd HH:mm:ss') //returns NULL, which is silly because this was the result from the 2nd example

It does not accept the T and Z , however the conversion result for a "clean" date has the T . But if I try the reverse operation, it returns null.

Answer 1

Flink knows two representations of timestamps in string format: SQL and ISO-8601 .

The SQL one follows 2021-12-16 20:29:37 and is accepted by TO_TIMESTAMP . It is also the result of a CAST(ts AS STRING) .

The ISO-8601 follows 2021-12-16T20:29:37 and might be accepted by future built-in utility functions.

The questions is: How do you "leave the SQL world" by printing? If you stay in the table ecosystem and call table.execute().print() future Flink versions will print the SQL format. Also the SQL Client will do this. At least this will be the behavior in Flink 1.15 and might already be the case in Flink 1.14.

If you do table.execute().collect().forEach(println) you print "via the Java world" which means that java.time.LocalDateTime.toString is called which uses ISO-8601 format.