MySQL如何合并语句

Question

1. 我有两个陈述

一种。

while (($row_1 = $STH_1 -> fetch_assoc()) !== null){
    $table_name = $row_1['table_name']; 
    $stmts_1[] = sprintf("                       
        SELECT *                         
        FROM $table_name                         
        WHERE date_time = $today_date ");
}

$stmt_1 = implode("\nUNION\n", $stmts_1);   
$stmt_1 .= "\nORDER BY date_time ASC";    
$STH_5_2 = $DBH_R->query($stmt_1);  
while (($row_5_2 = $STH_5_2 -> fetch_assoc()) !== null) {   }  

b。

$STH_e = $DBH_R->query("                         
    SELECT *                                                  
    FROM $table_name_2                                                  
    WHERE date_time = $today_date  ");   
while (($row_e = $STH_e -> fetch_assoc()) !== null) {   } 

1. 查询1和查询2的源列不同
2. 一列类似-> date_time，但是TIME（date_time）不同，DATE（date_time）相同
3. 我必须合并为一个列表（ORDER BY TIME（date_time）ASC）以创建股票代码的来源

问：如何合并这两个语句？ 还是这两个查询？

// ------------------------------------------------ -------------更新-创建表语句

1. 查询表1-此类型接近30个表

   如果不存在则创建表v_c_ei_9001 （

   id int（11）unsigned NOT NULL AUTO_INCREMENT，

   ei_code int（10）非空默认值'0'，

   date_time datetime不是NULL缺省'0000-00-00 00:00:00'，

   index_year varchar（10）NOT NULL缺省'ndnc'，

   index_period varchar（10）NOT NULL默认值'nd'，

   index_period_2 varchar（10）NOT NULL默认值'nd'，

   index_unit varchar（10）NOT NULL默认值'nd'，

   index_comment文字NOT NULL，

   主键（ id ），键date_time （ date_time ））ENGINE = MyISAM DEFAULT CHARSET = utf8 AUTO_INCREMENT = 608;

2. 查询表2-此类型仅一个

   如果不存在则创建表v_c_e （

   id int（11）unsigned NOT NULL AUTO_INCREMENT，

   country_code int（10）非空默认值'0'，

   country_name varchar（50）NOT NULL默认'ndnc'，

   date_time datetime不是NULL缺省'0000-00-00 00:00:00'，

   event_title varchar（100）NOT NULL DEFAULT'ndnc'，

   event_released int（10）NOT NULL默认值'0'，

   event_comment varchar（500）NOT NULL DEFAULT'ndnc'，

   主键（ id ））ENGINE = MyISAM DEFAULT CHARSET = utf8 AUTO_INCREMENT = 168;

g

// ------------------------------------------------ -更新2

预查询代码//从数据库中的所有表中，我们仅查询名称类似于v_c_ei_9xxx的表

$STH_1 = $DBH_R->query("SELECT table_name                        
                         FROM information_schema.tables                        
                        WHERE table_name                        
                         LIKE 'v_c_ei\_9%'
                         ");
$stmts_1 = array();

while (($row_1 = $STH_1 -> ..... // as above

Answer 1

  $stmts_1[] = sprintf("
SELECT * FROM (
   SELECT *                         
   FROM $table_name tn                     
   WHERE date_time = $today_date

UNION ALL

SELECT *                                                  
   FROM $table_name_2 tn2                                                  
   WHERE date_time = $today_date
)tmp;"                       

}

那应该做您想要的-根据传递的变量，我还没有测试它，并且您没有提供SQL或代码。 这是一个子选择查询。 UNION ALL部分将两个查询的结果连接为一个结果。 但是，两个表必须以相同的顺序具有相同数量的列，否则将引发不兼容的类型或错误的列错误数量。

相反，最好定义列和顺序，例如

  $stmts_1[] = sprintf("
SELECT * FROM (
SELECT col1, col2, col3, col4...... coln                          
FROM $table_name tn                     
WHERE date_time = $today_date

UNION ALL

SELECT col1, col2, col3, col4...... coln                                            
   FROM $table_name_2 tn2                                                 
   WHERE date_time = $today_date
)tmp;"

}

编辑：

应用我上面说过的相同逻辑，您可以处理一个表中的其他属性，而不能像这样处理另一个表：

SELECT * FROM(

SELECT
id as id,
ei_code as ei_code,
date_time as dt,
'' as country_name,
index_year as iy,
index_period as ip1,
index_period_2 as ip2,
index_unit as iu,
index_comment as ic,
'' as et,
'' as er,
'' as ec
  FROM `v_c_ei_9001` vce1

UNION ALL

SELECT
id as id,
country_code as country_code,
date_time as date_time,
country_name as country_name,
'' as iy,
'' as ip1,
'' as ip2,
'' as iu,
'' as ic,
event_title as et,
event_released as er,
event_comment as ec
FROM  `v_c_e` as vce2

)tmp

我基于您发布的创建表做了几个假设，因为输入掩码非常相似。 如果这些错误在您的上下文中是错误的，请像我对ip1，ip2等所做的那样创建空白字段。

编辑2：

$start2 = "SELECT
id as id,
country_code as country_code,
date_time as date_time,
country_name as country_name,
'' as iy,
'' as ip1,
'' as ip2,
'' as iu,
'' as ic,
event_title as et,
event_released as er,
event_comment as ec
FROM "; 

$count = 0;

$start = "SELECT
id as id,
ei_code as ei_code,
date_time as date_time,
'' as country_name,
index_year as iy,
index_period as ip1,
index_period_2 as ip2,
index_unit as iu,
index_comment as ic,
'' as et,
'' as er,
'' as ec
  FROM ";
//Loop through all table names using the variable $start concatenated with $table_name to create the SQL statement you require
while (($row_1 = $STH_1 -> fetch_assoc()) !== null){
    $table_name = $row_1['table_name']; 
    $stmts_1[] = sprintf("                       
        $start $table_name                         
         WHERE date_time = $today_date ");
    $count = $count + 1;
}

//This statements adds an extra String to the above stmt_1 - the $count variable controls where the extra string is placed, should be at the end of the array. Shouldn't matter though.
//NOTE this is your second query the part 'b' of your above question: variable $table_name_2
    $stmt_1[count] sprintf("                       
            $start2 $table_name_2                         
             WHERE date_time = $today_date ");

//Implode all arrays into one long array adding 'Carriage Return (\n) UNION Carriage Return (\n)' between each statement.

    $stmt_1 = implode("\nUNION\n", $stmts_1);  
    //Add another line at the end for the order by
    $stmt_1 .= "\nORDER BY date_time ASC";    
    $STH_5_2 = $DBH_R->query($stmt_1);  
    while (($row_5_2 = $STH_5_2 -> fetch_assoc()) !== null) {   }