DatabaseChecker

All Implemented Interfaces:
```
public class DatabaseChecker

                    
```
check the timezone between mysql server, application, and jdbc session. see time-zone-variables

Since:

2021-04-14

Author:

trydofor

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description

Field Summary

Fields
Modifier and Type	Field	Description

Constructor Summary

Constructors
Constructor	Description
`DatabaseChecker()`

Enum Constant Summary

Enum Constants
Enum Constant	Description

Method Summary

Modifier and Type	Method	Description
`static boolean`	`isH2(DataSource ds)`	Whether in H2database
`static String`	`extractJdbcUrl(DataSource ds)`	Extract the jdbc-url from the datasource
`static void`	`timezone(DataSource ds)`	Check timezone with off=5, fail=true
`static void`	`timezone(DataSource ds, int off, boolean fail)`	Check the database and jvm time difference, in the absolute `off` second, throw or log as ERROR if `fail`.
`static long`	`version(DataSource ds)`	output the database version in the log, return flywave revision if found
`static boolean`	`existTable(Connection conn, String table)`	Whether the table exist, need close the `conn` manually.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - DatabaseChecker
```
DatabaseChecker()
```
- Method Detail
  - isH2
```
 static boolean isH2(DataSource ds)
```
    Whether in H2database
  - extractJdbcUrl
```
@NotNull() static String extractJdbcUrl(DataSource ds)
```
    Extract the jdbc-url from the datasource
  - timezone
```
 static void timezone(DataSource ds)
```
    Check timezone with off=5, fail=true
  - timezone
```
 static void timezone(DataSource ds, int off, boolean fail)
```
    Check the database and jvm time difference, in the absolute `off` second, throw or log as ERROR if `fail`.
    
    Parameters:
    
    ds - datasource
    
    off - max abs time tolerance in second
    
    fail - throw IllegalStateException or log.
  - version
```
 static long version(DataSource ds)
```
    output the database version in the log, return flywave revision if found
  - existTable
```
 static boolean existTable(Connection conn, String table)
```
    Whether the table exist, need close the `conn` manually. `SELECT 1 FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME=? AND TABLE_SCHEMA=SCHEMA()` current-schema-function