使用 SQL 语句获取数据库中的字段数？
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Getting number of fields in a database with an SQL Statement?
提问by Ash
How would I get the number of fields/entries in a database using an SQL Statement?
如何使用 SQL 语句获取数据库中的字段/条目数？
回答by Jhonny D. Cano -Leftware-
mmm all the fields in all the tables? assuming standards (mssql, mysql, postgres) you can issue a query over information_schema.columns
mmm 所有表中的所有字段？假设标准（mssql、mysql、postgres），您可以对 information_schema.columns 发出查询
SELECT COUNT(*)
FROM INFORMATION_SCHEMA.COLUMNS
Or grouped by table:
或按表分组：
SELECT TABLE_NAME, COUNT(*)
FROM INFORMATION_SCHEMA.COLUMNS
GROUP BY TABLE_NAME
If multiple schemas has the same table name in the same DB, you MUST include schema name as well (i.e: dbo.Books, user.Books, company.Books etc.) Otherwise you'll get the wrong results. So the best practice is:
如果多个模式在同一个数据库中具有相同的表名，则还必须包括模式名（即：dbo.Books、user.Books、company.Books 等），否则会得到错误的结果。所以最好的做法是：
SELECT TABLE_SCHEMA, TABLE_NAME, COUNT(*)
FROM INFORMATION_SCHEMA.COLUMNS
GROUP BY TABLE_SCHEMA, TABLE_NAME
回答by SQLMenace
try this, this will exclude views, leave the where clause out if you want views
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'
回答by Scott Ivey
Sounds like this is what you need.
听起来这就是你所需要的。
select CountOfFieldsInDatabase = count(*)
from information_schema.columns
回答by hye ji
select count(column_name) from information_schema.columns
where table_name = **name of your table here **
回答by jcansell
Just for any other readers who are googling...
仅适用于使用谷歌搜索的任何其他读者......
There are several non-SQL solutions, that may be useful to the user.. here's 2 that I use.
有几个非 SQL 解决方案，可能对用户有用..这是我使用的 2 个。
Example 1: Access VBA:
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
Example 2: PHP 5.1:
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;
?>
please excuse any typo's in the above - hope someone finds this useful
请原谅上面的任何错字 - 希望有人觉得这有用
