Oracle的user_talbes用於記錄了用戶表信息。
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select * from user_tables |
獲取某個表的字段：
USER_TAB_COLS中記錄了用戶表的列信息。下面是別人寫的：
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SELECT USER_TAB_COLS.TABLE_NAME as 表名,USER_TAB_COLS.COLUMN_NAME as 列名 , USER_TAB_COLS.DATA_TYPE as 數據類型, USER_TAB_COLS.DATA_LENGTH as 長度, USER_TAB_COLS.NULLABLE as 是否爲空,USER_TAB_COLS.COLUMN_ID as 列序號,user_col_comments.comments as 備註 FROM USER_TAB_COLS inner join user_col_comments on user_col_comments.TABLE_NAME=USER_TAB_COLS.TABLE_NAME and user_col_comments.COLUMN_NAME=USER_TAB_COLS.COLUMN_NAME |
如何從Oracle、中取得表的註釋
user_tab_comments;表註釋
user_col_comments;表字段註釋
以上兩個只能獲取自己用戶的表的註釋信息，如果要訪問自己能夠訪問的其他用戶的表，則需要使用：
all_tab_comments;表註釋
all_col_comments;表字段註釋
當然，如果有DBA權限，則可以使用
dba_tab_comments;表註釋
dba_col_comments;表字段註釋
dba*和all*最好指定owner條件。user*沒有該字段
user_tab_comments;表註釋
user_col_comments;表字段註釋
以上兩個只能獲取自己用戶的表的註釋信息，如果要訪問自己能夠訪問的其他用戶的表，則需要使用：
all_tab_comments;表註釋
all_col_comments;表字段註釋
當然，如果有DBA權限，則可以使用
dba_tab_comments;表註釋
dba_col_comments;表字段註釋
dba*和all*最好指定owner條件。user*沒有該字段
關於Oracle與SqlServer中獲取所有字段、主鍵、外鍵的sql語句 標籤： 主鍵 外鍵 sql
最近在做的社會網絡分析原型系統需要將多種不同數據庫中的表的字段、主外鍵信息讀出，實現這些功能費了不少功夫，記錄下來以備用吧
Oracle:
查詢某個表中的字段名稱、類型、精度、長度、是否爲空
select COLUMN_NAME,DATA_TYPE,DATA_PRECISION,DATA_SCALE,NULLABLE
from user_tab_columns
where table_name ='YourTableName'
查詢某個表中的主鍵字段名
select col.column_name
from user_constraints con, user_cons_columns col
where con.constraint_name = col.constraint_name
and con.constraint_type='P'
and col.table_name = 'YourTableName'
查詢某個表中的外鍵字段名稱、所引用表名、所應用字段名
select distinct(col.column_name),r.table_name,r.column_name
from
user_constraints con,
user_cons_columns col,
(select t2.table_name,t2.column_name,t1.r_constraint_name
from user_constraints t1,user_cons_columns t2
where t1.r_constraint_name=t2.constraint_name
and t1.table_name='YourTableName'
) r
where con.constraint_name=col.constraint_name
and con.r_constraint_name=r.r_constraint_name
and con.table_name='YourTableName'
SQLServer中的實現：
字段：
SELECT c.name,t.name,c.xprec,c.xscale,c.isnullable
FROM systypes t,syscolumns c
WHERE t.xtype=c.xtype
AND c.id = (SELECT id FROM sysobjects WHERE name='YourTableName')
ORDER BY c.colid
主鍵（參考SqlServer系統存儲過程sp_pkeys）：
select COLUMN_NAME = convert(sysname,c.name)
from
sysindexes i, syscolumns c, sysobjects o
where o.id = object_id('[YourTableName]')
and o.id = c.id
and o.id = i.id
and (i.status & 0x800) = 0x800
and (c.name = index_col ('[YourTableName]', i.indid, 1) or
c.name = index_col ('[YourTableName]', i.indid, 2) or
c.name = index_col ('[YourTableName]', i.indid, 3) or
c.name = index_col ('[YourTableName]', i.indid, 4) or
c.name = index_col ('[YourTableName]', i.indid, 5) or
c.name = index_col ('[YourTableName]', i.indid, 6) or
c.name = index_col ('[YourTableName]', i.indid, 7) or
c.name = index_col ('[YourTableName]', i.indid, 8) or
c.name = index_col ('[YourTableName]', i.indid, 9) or
c.name = index_col ('[YourTableName]', i.indid, 10) or
c.name = index_col ('[YourTableName]', i.indid, 11) or
c.name = index_col ('[YourTableName]', i.indid, 12) or
c.name = index_col ('[YourTableName]', i.indid, 13) or
c.name = index_col ('[YourTableName]', i.indid, 14) or
c.name = index_col ('[YourTableName]', i.indid, 15) or
c.name = index_col ('[YourTableName]', i.indid, 16)
)
外鍵：
select t1.name,t2.rtableName,t2.name
from
(select col.name, f.constid as temp
from syscolumns col,sysforeignkeys f
where f.fkeyid=col.id
and f.fkey=col.colid
and f.constid in
( select distinct(id)
from sysobjects
where OBJECT_NAME(parent_obj)='YourTableName'
and xtype='F'
)
) as t1 ,
(select OBJECT_NAME(f.rkeyid) as rtableName,col.name, f.constid as temp
from syscolumns col,sysforeignkeys f
where f.rkeyid=col.id
and f.rkey=col.colid
and f.constid in
( select distinct(id)
from sysobjects
where OBJECT_NAME(parent_obj)='YourTableName'
and xtype='F'
)
) as t2
where t1.temp=t2.temp
就是這些，都是平時積累下來的，摘自己需要的用吧。
public static void test() {
Connection conn = null;
Statement stat = null;
ResultSet rs = null;
StringBuffer stringBuffer = new StringBuffer();
stringBuffer.append("<html><head></head><body lang=ZH-CN style='tab-interval:21.0pt;text-justify-trim:punctuation'>");
List<Object[]> objArrList = new ArrayList<Object[]>();
try {
conn = Pub.getConn();
stat = conn.createStatement();
String sql = "select * from user_tab_comments";
System.out.println("sql=="+sql);
rs = stat.executeQuery(sql);
int i = 0;
while (rs.next()) {
i ++;
String table_name = rs.getString("TABLE_NAME");
String comments = rs.getString("COMMENTS");
Object[] objArr = new Object[3];
objArr[0] = i;
objArr[1] = table_name;
objArr[2] = comments;
objArrList.add(objArr);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
Pub.close(conn, stat, rs);
}
for (int i = 0; i < objArrList.size(); i++) {
Object[] objArr = objArrList.get(i);
String table_name = objArr[1].toString();
String comments = objArr[2].toString();
stringBuffer.append("<font size=\"5\">").append("<strong>").append(objArr[0].toString()).append("、").append(comments).append(" ").append(table_name).append("</strong>").append("</font>").append("\n");
stringBuffer.append("<table border=1 cellspacing=0 cellpadding=0 style='border-collapse:collapse;border:none;mso-border-alt:solid black .5pt; mso-border-themecolor:text1;mso-yfti-tbllook:1184;mso-padding-alt:0cm 5.4pt 0cm 5.4pt'>");
stringBuffer.append("<tr style='mso-yfti-irow:0;mso-yfti-firstrow:yes'>");
stringBuffer.append("<td width=95 valign=top style='background-color:#ccc;border:solid black 1.0pt;'>").append("英文名").append("</td>");
stringBuffer.append("<td width=95 valign=top style='background-color:#ccc;border:solid black 1.0pt;'>").append("中文名").append("</td>");
stringBuffer.append("<td width=95 valign=top style='background-color:#ccc;border:solid black 1.0pt;'>").append("類型").append("</td>");
stringBuffer.append("<td width=95 valign=top style='background-color:#ccc;border:solid black 1.0pt;'>").append("長度").append("</td>");
stringBuffer.append("<td width=95 valign=top style='background-color:#ccc;border:solid black 1.0pt;'>").append("是否爲空").append("</td>");
stringBuffer.append("<td width=95 valign=top style='background-color:#ccc;border:solid black 1.0pt;'>").append("主鍵/外鍵").append("</td>");
stringBuffer.append("</tr>");
try {
conn = Pub.getConn();
stat = conn.createStatement();
String sql = "SELECT USER_TAB_COLS.COLUMN_NAME , USER_TAB_COLS.DATA_TYPE, USER_TAB_COLS.DATA_LENGTH,user_tab_cols.DATA_PRECISION,user_tab_cols.DATA_SCALE, USER_TAB_COLS.NULLABLE,user_col_comments.comments FROM USER_TAB_COLS inner join user_col_comments on user_col_comments.TABLE_NAME=USER_TAB_COLS.TABLE_NAME and user_col_comments.COLUMN_NAME=USER_TAB_COLS.COLUMN_NAME and user_col_comments.table_name='"+table_name+"' order by user_tab_cols.COLUMN_ID";
System.out.println("sql=="+sql);
rs = stat.executeQuery(sql);
boolean b = true;
while (rs.next()) {
String column_name = rs.getString("column_name");
String data_type = rs.getString("DATA_TYPE");
int data_length = rs.getInt("DATA_LENGTH");
int data_percision = rs.getInt("DATA_PRECISION");
int data_scale = rs.getInt("DATA_SCALE");
String nullable = rs.getString("NULLABLE");
String ccomments = rs.getString("COMMENTS");
String temp_data_length;
if ("NUMBER".equals(data_type)) {
if (data_scale == 0) {
temp_data_length = data_percision+"";
}else {
temp_data_length = data_percision+","+data_scale;
}
}else {
temp_data_length = data_length+ "";
}
String pk ="";
if (b) {
pk = "PK";
b = false;
}
stringBuffer.append("<tr style='mso-yfti-irow:0;mso-yfti-firstrow:yes'>");
stringBuffer.append("<td width=95 valign=top style='border:solid black 1.0pt;'>").append(column_name).append("</td>");
stringBuffer.append("<td width=95 valign=top style='border:solid black 1.0pt;'>").append(ccomments).append("</td>");
stringBuffer.append("<td width=95 valign=top style='border:solid black 1.0pt;'>").append(data_type).append("</td>");
stringBuffer.append("<td width=95 valign=top style='border:solid black 1.0pt;'>").append(temp_data_length).append("</td>");
stringBuffer.append("<td width=95 valign=top style='border:solid black 1.0pt;'>").append(nullable).append("</td>");
stringBuffer.append("<td width=95 valign=top style='border:solid black 1.0pt;'>").append(pk).append("</td>");
stringBuffer.append("</tr>");
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
Pub.close(conn, stat, rs);
}
stringBuffer.append("</table>");
stringBuffer.append("<br>");
}
stringBuffer.append("</body></html>");
FileOperate fo = new FileOperate();
fo.createFile("D:\\My Documents\\桌面", "寫中文文字.htm");
fo.writeFile("D:\\My Documents\\桌面\\寫中文文字.htm", stringBuffer.toString());
System.out.println(stringBuffer.toString());
}