Hive中concat()和concat_ws如何拼接空字符串

这篇文章主要介绍了Hive中concat()和concat_ws如何拼接空字符串，具有一定借鉴价值，感兴趣的朋友可以参考下，希望大家阅读完这篇文章之后大有收获，下面让小编带着大家一起了解一下。

concat() ：如果存在空，返回空：

hive> select concat('cd','1');OKcd1Time taken: 0.461 seconds, Fetched: 1 row(s)hive> select concat('cd',1);OKcd1Time taken: 0.066 seconds, Fetched: 1 row(s)hive> select concat('cd',null);OKNULLTime taken: 0.053 seconds, Fetched: 1 row(s)hive> select concat('null','cd');OKnullcdTime taken: 0.06 seconds, Fetched: 1 row(s)hive> select concat(null,'cd');OKNULLTime taken: 0.056 seconds, Fetched: 1 row(s)hive>

concat_ws:如果存在空，返回非空的拼接：

hive> select concat_ws('_','a','c','v','d');OKa_c_v_dTime taken: 0.06 seconds, Fetched: 1 row(s)hive> select concat_ws('_',null,'c','v','d');OKc_v_dTime taken: 0.047 seconds, Fetched: 1 row(s)hive> select concat_ws('_',null,'c',null,'d');OKc_dTime taken: 0.053 seconds, Fetched: 1 row(s)hive> select concat_ws(null,'a','c','v','d');OKNULLTime taken: 0.055 seconds, Fetched: 1 row(s)hive> hive> select concat_ws('_',null,'c',null);OKcTime taken: 0.072 seconds, Fetched: 1 row(s)hive> select concat_ws('_',null,null,null);OK Time taken: 0.049 seconds, Fetched: 1 row(s)hive>

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