如何插入“concat”？在现有的mysql查询？ [英] How do i insert a "concat" on existing mysql query?

问题描述

您好，



我有这个查询，我希望在（）之间连接值。我该怎么办呢？



Sql查询：

Hello,

I have this query that i want to concat the values in between the "()". How can i do it correctly?

Sql query:

string SQL = "SELECT a.id_veiculo, a.id_empresa, a.nome_condutor, a.empresa_visitante, a.empresa_visitar, a.visitado, a.ncartao, (a.data + a.hora) as 'Entrada', a.obs,a.sector, (b.data + b.hora) as 'Saida' FROM entradas a LEFT OUTER JOIN saidas b ON a.data = b.data AND a.hora = b.hora and a.sector WHERE id_empresa = @tabempresa; ";

编辑：

string SQL = "SELECT a.id_veiculo, a.id_empresa, a.ncartao, a.nome_condutor, a.empresa_visitante, a.empresa_visitar, a.visitado, CONCAT(a.data,a.hora) as 'Entrada',a.sector,a.obs, CONCAT(b.data,b.hora) as 'Saida' FROM entradas a LEFT OUTER JOIN saidas b ON a.data = b.data AND a.hora = b.hora and a.sector WHERE id_empresa = @tabempresa; ";

此字符串工作正常，但我的值如2016-03-0109：58：00，我想要它如此2016-03-01 / 09:58:00



我的尝试：



尝试使用CONCAT复制此字符串，我想要组合数据，如下所示：



string SQL =SELECT a .id_veiculo，a.id_empresa，a.nome_condutor，a.empresa_visitante，a.empresa_visitar，a.visitado，a.ncartao，CONCAT（a.data，a.hora）as'Entrada'，a.obs，a.sector， （b.data，b.hora）as'Seida'FROM entradas LEFT OUTER JOIN表示b on a.data = b.data AND a.hora = b.hora and a.sector WHERE id_empresa = @tabempresa;

This string works fine, but i have the value in it like "2016-03-0109:58:00" and i want it to be like so "2016-03-01 / 09:58:00"

What I have tried:

Tryied to replicate this string with the CONCAT where i wanted to combine data, like so:

string SQL = "SELECT a.id_veiculo, a.id_empresa, a.nome_condutor, a.empresa_visitante, a.empresa_visitar, a.visitado, a.ncartao, CONCAT(a.data, a.hora) as 'Entrada', a.obs,a.sector, (b.data, b.hora) as 'Saida' FROM entradas a LEFT OUTER JOIN saidas b ON a.data = b.data AND a.hora = b.hora and a.sector WHERE id_empresa = @tabempresa;

推荐答案

根据文档 [ ^ ]， C. ONCAT 函数接受多个字符串参数。您只需要在字段之间传递分隔符：

According to the documentation[^], the CONCAT function accepts multiple string arguments. You just need to pass the separator in between the fields:

CONCAT(a.data, ' / ', a.hora)

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