是否有一种方法可以获得MySQL数据库中所有表的行计数,而无需在每个表上运行SELECT count() ?
当前回答
如果你使用数据库information_schema,你可以使用下面的mysql代码(where部分使查询不显示行为空值的表):
SELECT TABLE_NAME, TABLE_ROWS
FROM `TABLES`
WHERE `TABLE_ROWS` >=0
其他回答
如果你知道表的数量和它们的名称,并且假设它们每个都有主键,你可以使用交叉连接结合COUNT(distinct [column])来获得来自每个表的行:
SELECT
COUNT(distinct t1.id) +
COUNT(distinct t2.id) +
COUNT(distinct t3.id) AS totalRows
FROM firstTable t1, secondTable t2, thirdTable t3;
下面是一个SQL Fiddle的例子。
你可以试试这个。这对我来说很好。
SELECT IFNULL(table_schema,'Total') "Database",TableCount
FROM (SELECT COUNT(1) TableCount,table_schema
FROM information_schema.tables
WHERE table_schema NOT IN ('information_schema','mysql')
GROUP BY table_schema WITH ROLLUP) A;
海报想要行计数,但没有指定哪个表引擎。对于InnoDB,我只知道一种方法,那就是计数。
我是这样摘土豆的:
# Put this function in your bash and call with:
# rowpicker DBUSER DBPASS DBNAME [TABLEPATTERN]
function rowpicker() {
UN=$1
PW=$2
DB=$3
if [ ! -z "$4" ]; then
PAT="LIKE '$4'"
tot=-2
else
PAT=""
tot=-1
fi
for t in `mysql -u "$UN" -p"$PW" "$DB" -e "SHOW TABLES $PAT"`;do
if [ $tot -lt 0 ]; then
echo "Skipping $t";
let "tot += 1";
else
c=`mysql -u "$UN" -p"$PW" "$DB" -e "SELECT count(*) FROM $t"`;
c=`echo $c | cut -d " " -f 2`;
echo "$t: $c";
let "tot += c";
fi;
done;
echo "total rows: $tot"
}
我对此没有任何断言,只是说这是一种非常丑陋但有效的方法,可以获得数据库中每个表中存在多少行,而不需要使用表引擎,也不需要拥有安装存储过程的权限,也不需要安装ruby或php。是的,生锈了。是的,这很重要。Count(*)是准确的。
这是我如何使用PHP计算表和所有记录:
$dtb = mysql_query("SHOW TABLES") or die (mysql_error());
$jmltbl = 0;
$jml_record = 0;
$jml_record = 0;
while ($row = mysql_fetch_array($dtb)) {
$sql1 = mysql_query("SELECT * FROM " . $row[0]);
$jml_record = mysql_num_rows($sql1);
echo "Table: " . $row[0] . ": " . $jml_record record . "<br>";
$jmltbl++;
$jml_record += $jml_record;
}
echo "--------------------------------<br>$jmltbl Tables, $jml_record > records.";
还有一个选择:对于非InnoDB,它使用information_schema中的数据。TABLES(因为它更快),对于InnoDB -选择count(*)来获得准确的计数。它还会忽略视图。
SET @table_schema = DATABASE();
-- or SET @table_schema = 'my_db_name';
SET GROUP_CONCAT_MAX_LEN=131072;
SET @selects = NULL;
SELECT GROUP_CONCAT(
'SELECT "', table_name,'" as TABLE_NAME, COUNT(*) as TABLE_ROWS FROM `', table_name, '`'
SEPARATOR '\nUNION\n') INTO @selects
FROM information_schema.TABLES
WHERE TABLE_SCHEMA = @table_schema
AND ENGINE = 'InnoDB'
AND TABLE_TYPE = "BASE TABLE";
SELECT CONCAT_WS('\nUNION\n',
CONCAT('SELECT TABLE_NAME, TABLE_ROWS FROM information_schema.TABLES WHERE TABLE_SCHEMA = ? AND ENGINE <> "InnoDB" AND TABLE_TYPE = "BASE TABLE"'),
@selects) INTO @selects;
PREPARE stmt FROM @selects;
EXECUTE stmt USING @table_schema;
DEALLOCATE PREPARE stmt;
如果你的数据库有很多大的InnoDB表,计算所有行会花费更多的时间。