我想把我的iPhone应用程序迁移到一个新的数据库版本。由于我没有保存一些版本,我需要检查是否存在某些列名。

这个Stackoverflow条目建议执行选择

SELECT sql FROM sqlite_master
WHERE tbl_name = 'table_name' AND type = 'table'

并解析结果。

这是常见的方式吗?选择呢?


当前回答

这是一个老问题,但这里有一个替代答案,检索SQLite数据库中的所有列,并为每列提供关联表的名称:

WITH tables AS (SELECT name tableName, sql 
FROM sqlite_master WHERE type = 'table' AND tableName NOT LIKE 'sqlite_%')
SELECT fields.name, fields.type, tableName
FROM tables CROSS JOIN pragma_table_info(tables.tableName) fields

返回这样的结果:

{
    "name": "id",
    "type": "integer",
    "tableName": "examples"
}, {
    "name": "content",
    "type": "text",
    "tableName": "examples"
}

对于包含标识符和字符串内容的简单表。

其他回答

我知道这是一个旧的帖子,但最近我需要同样的帖子,并找到了一个简洁的方法:

SELECT c.name FROM pragma_table_info('your_table_name') c;

. schema 在sqlite控制台中,你在表中 在我看来是这样的……

sqlite>.schema
CREATE TABLE players(
id integer primary key,
Name varchar(255),
Number INT,
Team varchar(255)
function getDetails(){
var data = [];
dBase.executeSql("PRAGMA table_info('table_name') ", [], function(rsp){
    if(rsp.rows.length > 0){
        for(var i=0; i<rsp.rows.length; i++){
            var o = {
                name: rsp.rows.item(i).name,
                type: rsp.rows.item(i).type
            } 
            data.push(o);
        }
    }
    alert(rsp.rows.item(0).name);

},function(error){
    alert(JSON.stringify(error));
});             
}

为了获得列信息,你可以使用下面的代码片段:

String sql = "select * from "+oTablename+" LIMIT 0";
Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery(sql);
ResultSetMetaData mrs = rs.getMetaData();
for(int i = 1; i <= mrs.getColumnCount(); i++)
{
    Object row[] = new Object[3];
    row[0] = mrs.getColumnLabel(i);
    row[1] = mrs.getColumnTypeName(i);
    row[2] = mrs.getPrecision(i);
}

下面的命令设置列名:

.header on

然后,它是这样的:

sqlite> select * from user;
id|first_name|last_name|age
1|Steve|Jobs|56
2|Bill|Gates|66
3|Mark|Zuckerberg|38

下面的命令取消设置列名:

.header off

然后,它是这样的:

sqlite> select * from user;
1|Steve|Jobs|56
2|Bill|Gates|66
3|Mark|Zuckerberg|38

这些命令显示了".header"命令的详细信息:

.help .header

Or:

.help header

然后,它是这样的:

sqlite> .help .header
.headers on|off          Turn display of headers on or off

此外,下面的命令设置输出模式“box”:

.mode box

然后,它是这样的:

sqlite> select * from user;
┌────┬────────────┬────────────┬─────┐
│ id │ first_name │ last_name  │ age │
├────┼────────────┼────────────┼─────┤
│ 1  │ Steve      │ Jobs       │ 56  │
│ 2  │ Bill       │ Gates      │ 66  │
│ 3  │ Mark       │ Zuckerberg │ 38  │
└────┴────────────┴────────────┴─────┘

并且,下面的命令设置输出模式“table”:

.mode table

然后,它是这样的:

sqlite> select * from user;
+----+------------+------------+-----+
| id | first_name | last_name  | age |
+----+------------+------------+-----+
| 1  | Steve      | Jobs       | 56  |
| 2  | Bill       | Gates      | 66  |
| 3  | Mark       | Zuckerberg | 38  |
+----+------------+------------+-----+

这些命令显示了命令".mode"的详细信息:

.help .mode

Or:

.help mode

然后,它是这样的:

sqlite> .help .mode
.import FILE TABLE       Import data from FILE into TABLE
   Options:
     --ascii               Use \037 and \036 as column and row separators
     --csv                 Use , and \n as column and row separators
     --skip N              Skip the first N rows of input
     --schema S            Target table to be S.TABLE
     -v                    "Verbose" - increase auxiliary output
   Notes:
     *  If TABLE does not exist, it is created.  The first row of input
        determines the column names.
     *  If neither --csv or --ascii are used, the input mode is derived
        from the ".mode" output mode
     *  If FILE begins with "|" then it is a command that generates the
        input text.
.mode MODE ?OPTIONS?     Set output mode
   MODE is one of:
     ascii       Columns/rows delimited by 0x1F and 0x1E
     box         Tables using unicode box-drawing characters
     csv         Comma-separated values
     column      Output in columns.  (See .width)
     html        HTML <table> code
     insert      SQL insert statements for TABLE
     json        Results in a JSON array
     line        One value per line
     list        Values delimited by "|"
     markdown    Markdown table format
     qbox        Shorthand for "box --width 60 --quote"
     quote       Escape answers as for SQL
     table       ASCII-art table
     tabs        Tab-separated values
     tcl         TCL list elements
   OPTIONS: (for columnar modes or insert mode):
     --wrap N       Wrap output lines to no longer than N characters
     --wordwrap B   Wrap or not at word boundaries per B (on/off)
     --ww           Shorthand for "--wordwrap 1"
     --quote        Quote output text as SQL literals
     --noquote      Do not quote output text
     TABLE          The name of SQL table used for "insert" mode