如何使用SQL语句获取数据库中的字段/条目数?
答案 0 :(得分:27)
mmm所有表中的所有字段?假设标准(mssql,mysql,postgres),您可以通过information_schema.columns发出查询
SELECT COUNT(*)
FROM INFORMATION_SCHEMA.COLUMNS
或按表格分组:
SELECT TABLE_NAME, COUNT(*)
FROM INFORMATION_SCHEMA.COLUMNS
GROUP BY TABLE_NAME
如果多个模式在同一个DB中具有相同的表名,那么您还必须包含模式名称(即:dbo.Books,user.Books,company.Books等)。否则,您将得到错误的结果。所以最好的做法是:
SELECT TABLE_SCHEMA, TABLE_NAME, COUNT(*)
FROM INFORMATION_SCHEMA.COLUMNS
GROUP BY TABLE_SCHEMA, TABLE_NAME
答案 1 :(得分:4)
试试这个,这将排除视图,如果你想要视图,请保留where子句
select count(*) from information_schema.columns c
join information_schema.tables t on c.table_name = t.table_name
and t.table_type = 'BASE TABLE'
答案 2 :(得分:1)
听起来这就是你所需要的。
select CountOfFieldsInDatabase = count(*)
from information_schema.columns
答案 3 :(得分:0)
select count(column_name) from information_schema.columns
where table_name = **name of your table here **
答案 4 :(得分:0)
对于任何其他谷歌搜索的读者......
有几种非SQL解决方案,可能对用户有用.. 这是我用的2个。
示例1: 访问VBA:
'Microsoft Access VBA
Function Count_Fields(Table_Name As String) As Integer
Dim myFieldCount As Integer
Dim db As DOA.Database
Dim rs As DAO.Recordset
Set db = CurrentDb
Set rs = db.OpenRecordset(Table_Name, dbOpenDynaset)
myFieldCount = rs.Fields.Count
'return the count
Count_Fields = myFieldCount
'tidy up
Set rs = Nothing
Set db = Nothing
End Function
示例2: PHP 5.1:
<?php
// PHP5 Implementation - uses MySQLi.
function countFields ($tableName) {
$db = new mysqli('myserver.me.com', 'user' ,'pass', 'databasename');
if(!$db) {
echo 'ERROR: Could not connect to the database.';
}
else {
$rs->$db->query("SELECT * FROM ".$tableName.");
$fieldCount = $rs->field_count;
}
return $fieldCount;
?>
请原谅上面的任何拼写错误 - 希望有人发现这个有用的