Last modified by christoph_lechleitner@iteg_at on 2013-01-31 07.32:56
From version 2.1
edited by 5fbc055b7cc103006957e1ae
on 2012-06-14 06.29:38
on 2012-06-14 06.29:38
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To version 7.1
edited by christoph_lechleitner@iteg_at
on 2013-01-31 07.32:55
on 2013-01-31 07.32:55
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... ... @@ -1,27 +1,78 @@ 1 1 = {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Preliminary"/}}Preliminary = 2 2 3 -The SchemaManager and SchemaEngine giveyouanabstractedaccessto the database schemaofyourapplication, allowing you to add and delete tables, columns, relations and data in the database on application updates.It uses a designated table to keep track of the current schema status, which it will check whenever it is run, and update the database if it is not at the correct version.3 +The SchemaManager ({{code language="none"}}org.clazzes.jdbc2xml.schema.SchemaManager{{/code}}) and SchemaEngine provide means to maintain the database scheme of an application, allowing you to add and delete tables, columns, relations and data in the database along application updates. 4 4 5 - SchemaManager({{codelanguage="none"}}org.clazzes.jdbc2xml.schema.SchemaManager{{/code}}) willcreateatablecalledSCHEMA_HISTORY if it cannot find itthefirst timeit isrun.This tablecontainsthe followingcolumns:5 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-SchemaHistoryTable"/}}Schema History Table === 6 6 7 -{{code language="none"}} 8 -VERSION:varchar(10), not null, primary key 9 -DESCRIPTION:varchar(512), nullable 10 -CREATION_DATE:date, nullable 11 -SERIALNR:integer(5), not null 12 -{{/code}} 7 +A designated schema table, by default named SCHEMA_HISTORY, is used to keep track of the current scheme. It will be automatically at SchemaManager's first run. (% style="font-size: 10.0pt;line-height: 13.0pt;" %)SCHEMA_HISTORY contains the following columns: 13 13 9 +|=((( 10 + 11 +)))|=((( 12 + 13 +))) 14 +|((( 15 +(% class="code" %) 16 +((( 17 +VERSION 18 +))) 19 +)))|((( 20 +(% class="code" %) 21 +((( 22 +varchar(10), not null, primary key 23 +))) 24 +))) 25 +|((( 26 +(% class="code" %) 27 +((( 28 +DESCRIPTION 29 +))) 30 +)))|((( 31 +(% class="code" %) 32 +((( 33 +varchar(512), nullable 34 +))) 35 +))) 36 +|((( 37 +(% class="code" %) 38 +((( 39 +CREATION_DATE 40 +))) 41 +)))|((( 42 +(% class="code" %) 43 +((( 44 +date, nullable 45 +))) 46 +))) 47 +|((( 48 +(% class="code" %) 49 +((( 50 +SERIALNR 51 +))) 52 +)))|((( 53 +(% class="code" %) 54 +((( 55 +integer(5), not null 56 +))) 57 +))) 58 + 59 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-CustomnameforSchemaHistoryTable"/}}Custom name for Schema History Table === 60 + 61 +(% style="font-size: 10.0pt;line-height: 13.0pt;" %)In (% style="font-size: 10.0pt;font-weight: normal;line-height: 13.0pt;" %)heterogenous environments as well as in heavily modularized software architectures a single database may be shared by multiple parties each requiring a couple of tables. 62 + 63 +(% style="font-size: 10.0pt;font-weight: normal;line-height: 13.0pt;" %)To allow multiple modules (applications, libraries, other OSGi bundles) to use (% style="font-size: 10.0pt;line-height: 13.0pt;" %)JDBC2XML's SchemaManager concurrently within one database, as of JDBC 1.1.1 SchemaManager hold the name of the schema history table in an overwritable property, {{code language="none"}}versionHistoryTable{{/code}}. See (%%)[[JDBCTOXML-11>>url:https://jira.clazzes.org/browse/JDBCTOXML-11||shape="rect"]](% style="font-size: 10.0pt;line-height: 13.0pt;" %). 64 + 14 14 = {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-ProjectConfiguration"/}}Project Configuration = 15 15 16 - To function correctly,SchemaManagerneeds a DataSource ({{code language="none"}}javax.sql.DataSource{{/code}}) and a list of TableInfo ({{code language="none"}}org.clazzes.jdbc2xml.schema.TableInfo{{/code}}) Objects, from whichadatabase will be created ifit findsan empty database.Tofunctionproperly, it alsoneedsan implementation of ISchemaEngine ({{code language="none"}}org.clazzes.jdbc2xml.schema.ISchemaEngine{{/code}}).67 +SchemaManager requires a DataSource ({{code language="none"}}javax.sql.DataSource{{/code}}) and a list of TableInfo ({{code language="none"}}org.clazzes.jdbc2xml.schema.TableInfo{{/code}}) Objects, from which database structures will be created if an "empty" database is detected. Furthermore, an implementation of ISchemaEngine ({{code language="none"}}org.clazzes.jdbc2xml.schema.ISchemaEngine{{/code}}) is required. 17 17 18 -Optionally, you mayset thebase version (default value 0.1.00) and base description String (default "initial database schema").69 +Optionally, a base version (default value 0.1.00) and a base description String (default "initial database schema") may be specified. 19 19 20 20 Database updates are passed as a Map<String, ISchemaUpdateSnippet> (org.clazzes.jdbc2xml.schema.ISchemaUpdateSnippet) - details see below. 21 21 22 22 To perform the operations, call {{code language="none"}}SchemaManager.start(){{/code}}. 23 23 24 -=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets- UsingSpringorOSGi/Blueprint"/}}Using Spring or OSGi/Blueprint ===75 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-ConfigurationusingSpringorOSGi/Blueprint"/}}Configuration using Spring or OSGi/Blueprint === 25 25 26 26 If you are using OSGi with Blueprint or Spring to set up your project, you can configure a SchemaManager instance by adding the following to your blueprint {{code language="none"}}services.xml{{/code}} (or Spring configuration file): 27 27 ... ... @@ -33,7 +33,7 @@ 33 33 </bp:reference> 34 34 35 35 <bp:bean id="sqlDialect" factory-ref="dialectFactory" factory-method="newDialect"> 36 -<bp:argument ><!--PassJDBCURLas an argument-->87 +<bp:argument ref="jdbcUrl"><!-- bean jdbcUrl specified above --> 37 37 </bp:argument> 38 38 </bp:bean> 39 39 ... ... @@ -41,28 +41,46 @@ 41 41 <bp:property name="dialect" ref="sqlDialect"> 42 42 </bp:property> 43 43 </bp:bean> 95 + 44 44 97 +<bp:bean id="initialSchema" class="foo.schema.InitialSchema"></bp:bean> 98 + 45 45 <bp:bean id="databaseSetup" class="org.clazzes.jdbc2xml.schema.SchemaManager" init-method="start"> 46 46 <bp:property name="dataSource" ref="dataSource"></bp:property> 47 47 <bp:property name="schemaEngine" ref="schemaEngine"></bp:property> 102 + <!-- optional but recommended: special name for schema history table: --> 103 + <bp:property name="versionHistoryTable" value="MYLIB_SCHEMA_HISTORY"/> 104 + <!-- optional but recommended: explicit first version --> 48 48 <bp:property name="baseVersion" value="0.1.00" /> 49 49 <bp:property name="baseTables"> 50 -<!-- Add List of TableDefinitions here --> 107 +<!-- List of TableDefinitions here (see below), typical: --> 108 + <bp:bean factory-ref="initialSchema" factory-method="getSchema" /> 51 51 </bp:property> 110 + <!-- Add Update-Snippets here, example for updates from 0.1.00 to 0.1.01 and on to 0.2.00 52 52 <bp:property name="upateSnippets"> 53 -<!-- Add Update-Snippets here --> 112 +<bp:map> 113 + <bp:entry key="0.1.00" value="foo.schema.SchemaUpdate_0_1_01"></bp:entry> 114 + <bp:entry key="0.1.01" value="foo.schema.SchemaUpdate_0_2_00"></bp:entry> 115 +</bp:map> 54 54 </bp:property> 117 + --> 55 55 </bp:bean> 56 56 {{/code}} 57 57 58 -By default, JDBC2XML provides an implementation of IDialectFactory and ISchemaEngineFactory as an OSGi service or via ServiceRegistry lookupfor Spring.121 +By default, JDBC2XML provides an implementation of IDialectFactory and ISchemaEngineFactory as an OSGi service or via ServiceRegistry for Spring. 59 59 60 60 = {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Settingupaninitialdatabaseschema"/}}Setting up an initial database schema = 61 61 62 -To createaninitialdatabaseschema, youwillneed to provideSchemaManagerwithalist of TableInfo objects. Therecommended way to do this is toprovideaclass in your projectwhich creates this list init'sconstructor and provides itthroughagetter. Youcaninstantiate this class in your Spring/Blueprintconfigas a singleton,and feed the provided List toSchemaManager.Anexample ofthis class couldlook likethis:125 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-InitalSchema(InitialTableList)"/}}Inital Schema (Initial Table List) === 63 63 127 +To create an initial database schema, SchemaManager needs a list of TableInfo objects. 128 + 129 +The recommended strategy is to create an InitialSchema class providing this list through a getter. 130 + 131 +(% style="font-size: 10.0pt;line-height: 13.0pt;" %)This is an example: 132 + 64 64 {{code language="java"}} 65 -package o rg.clazzes.example.jdbc2xml;134 +package foo.schema; 66 66 67 67 import java.sql.Types; 68 68 import java.util.Arrays; ... ... @@ -73,81 +73,225 @@ 73 73 import org.clazzes.jdbc2xml.schema.PrimaryKeyInfo; 74 74 import org.clazzes.jdbc2xml.schema.TableInfo; 75 75 76 -public class TableDefinitions{145 +public class InitialSchema { 77 77 78 - /* It is adviseable to provide the Strings used as names for tables and columns as 79 - constants, so they can be reused to build sql-statements */ 80 - public static final String TB_EXAMPLE_TABLE_NAME = "ADDRESSBOOK"; 81 - public static final String COL_EXAMPLE_ID = "ID"; 82 - public static final String COL_EXAMPLE_NAME = "NAME"; 83 - public static final String COL_EXAMPLE_ADDRESS_REF = "ADDRESS"; 84 - public static final String COL_EXAMPLE_BIRTHDAY = "BIRTHDAY"; 85 - 86 - /* ... */ 87 - 88 88 private List<TableInfo> setup; 89 89 90 - public TableDefinitions() {91 -/ *Create a table*/92 -TableInfo exampleTable = new TableInfo(T B_EXAMPLE_TABLE_NAME);149 + public InitialSchema() { 150 +// Create a table 151 +TableInfo exampleTable = new TableInfo(TableDefs.TABLENAME_ADDRESSBOOK); 93 93 exampleTable.setColumns( 94 94 Arrays.asList(new ColumnInfo[] { 95 -new ColumnInfo(COL_ EXAMPLE_ID, Types.BIGINT, 20, null, false, null,true),96 -new ColumnInfo(COL_ EXAMPLE_NAME, Types.VARCHAR, 256, null, false, null),97 -new ColumnInfo(COL_ EXAMPLE_ADDRESS_REF, Types.BIGINT, 20, null, true, null),98 -new ColumnInfo(COL_ EXAMPLE_BIRTHDAY, Types.DATE, 12, null, false, null)154 +new ColumnInfo(TableDefs.COL_ADDRESSBOOK_ID, Types.BIGINT, 20, null, false, null,true), 155 +new ColumnInfo(TableDefs.COL_ADDRESSBOOK_NAME, Types.VARCHAR, 256, null, false, null), 156 +new ColumnInfo(TableDefs.COL_ADDRESSBOOK_ADDRESS_REF, Types.BIGINT, 20, null, true, null), 157 +new ColumnInfo(TableDefs.COL_ADDRESSBOOK_BIRTHDAY, Types.DATE, 12, null, false, null) 99 99 })); 100 100 101 -/* Example for creating a foreign key reference */ 102 -exampleTable.setForeignKeys(Arrays.asList(new ForeignKeyInfo[] { 103 -new ForeignKeyInfo("FK_EXAMPLE_ADDRESS", COL_EXAMPLE_ADDRESS_REF, TB_ADDRESS, COL_ADDRESS_ID) 104 -})); 105 - 106 -/* Example for creating a primary key */ 160 +// Example for creating a primary key 107 107 exampleTable.setPrimaryKey( 108 -new PrimaryKeyInfo("PK_EXAMPLE", COL_ EXAMPLE_ID)162 +new PrimaryKeyInfo("PK_EXAMPLE", COL_ADDRESSBOOK_ID) 109 109 ); 110 110 111 -/* ... */ 165 +// Example for creating a foreign key reference 166 +exampleTable.setForeignKeys(Arrays.asList(new ForeignKeyInfo[] { 167 +new ForeignKeyInfo("FK_EXAMPLE_ADDRESS", TableDefs.COL_ADDRESSBOOK_ADDRESS_REF, TableDefs.TABLENAME_ADDRESSES, TableDefs.COL_ADDRESS_ID) 168 +})); 112 112 170 +// ... 171 + 113 113 this.setup = Arrays.asList( 114 114 exampleTable, 115 -/ *...*/174 +// ... 116 116 ); 117 117 118 118 } 119 119 120 - public List<TableInfo> getSe tup() {121 -return this.se tup;179 + public List<TableInfo> getSchema() { 180 +return this.schema; 122 122 } 123 123 124 124 } 125 125 {{/code}} 126 126 127 - Youmust inject{{codelanguage="none"}}TableDefinitions.getSetup(){{/code}} into {{codelanguage="none"}}SchemaManager.setBaseTables(){{/code}} before calling {{codelanguage="none"}}SchemaManager.start(){{/code}}.186 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-TableDefs,acentralplacefortableandcolumnnames"/}}TableDefs, a central place for table and column names === 128 128 129 - Using Blueprint/Spring,youcandothiswiththe followingsnippet:188 +You may have notice the usage of {{code language="none"}}TableDefs.*{{/code}} members. 130 130 131 -{{code language="none"}} 190 +Table and column names should never be re-typed everywhere as literals, it is highly recommended to use constants. 191 + 192 +Putting these constants in a dedicated class, say {{code language="none"}}TableDef{{/code}}, allows to use this as an easily accessible list of all tables and columns in the database. 193 + 194 +This is an example: 195 + 196 +{{code language="java"}} 197 +package foo.schema; 198 + 199 +public class TableDefs { 200 + 201 + // It is adviseable to provide the Strings used as names for tables and columns as constants, 202 + // so they can be reused savely to construct SQL statements 132 132 204 + // 0.1.00 205 + public static final String TABLENAME_ADDRESSBOOK = "ADDRESSBOOK"; 206 + public static final String COL_ADDRESSBOOK_ID = "ID"; 207 + public static final String COL_ADDRESSBOOK_NAME = "NAME"; 208 + public static final String COL_ADDRESSBOOK_ADDRESS_REF = "ADDRESS"; 209 + public static final String COL_ADDRESSBOOK_BIRTHDAY = "BIRTHDAY"; 210 + // 0.1.01 211 +public static final String COL_ADDRESSBOOK_GENDER = "GENDER"; 212 + 213 +} 133 133 {{/code}} 134 134 135 -= {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets- UpdatingadatabaseschemawithSchemaUpdateSnippets"/}}Updatinga databaseschemawithSchemaUpdateSnippets=216 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Triggeringthecreationoftheinitialschema"/}}Triggering the creation of the initial schema === 136 136 218 +(% style="font-size: 10.0pt;line-height: 13.0pt;" %)To trigger the creation of the initial schema when coming across an empty database, (% style="font-size: 10.0pt;line-height: 13.0pt;" %){{code language="none"}}InitialSchema.getSchema(){{/code}} has to be injected into (% style="font-size: 10.0pt;line-height: 13.0pt;" %){{code language="none"}}SchemaManager.setBaseTables(){{/code}} before calling (% style="font-size: 10.0pt;line-height: 13.0pt;" %){{code language="none"}}SchemaManager.start(){{/code}}. 219 + 220 +Using Blueprint/Spring, you can do this by inserting the following snippet in the bean definition for SchemaManager: 221 + 222 +{{code language="html/xml"}} 223 +<bp:bean id="initialSchema" class="foo.schema.InitialSchema"></bp:bean> 224 + 225 +<bp:property name="baseTables"> 226 +<bp:bean factory-ref="initialSchema" factory-method="getSchema" /> 227 +</bp:property> 228 + 229 +{{/code}} 230 + 231 += {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-UpdatingadatabaseschemawithISchemaUpdateSnippet"/}}Updating a database schema with ISchemaUpdateSnippet = 232 + 137 137 To update the database or it's content with schema updates, you must create a new implementation of ISchemaUpdateSnippet ({{code language="none"}}org.clazzes.jdbc2xml.schema.ISchemaUpdateSnippet{{/code}}) for each consecutive update. SchemaManager takes a {{code language="none"}}Map<String, Class<? extends ISchemaUpdateSnippet>>{{/code}} which contains the update classes keyed by the originating (e.g. previous) version. 138 138 139 - 235 +An example for an implementation of a schema update snippet could look like this: 140 140 141 - 237 +{{code language="java"}} 238 +package foo.schema; 142 142 143 - 240 +import java.sql.SQLException; 241 +import java.sql.Types; 242 +import java.util.Arrays; 243 +import org.clazzes.jdbc2xml.schema.ColumnInfo; 244 +import org.clazzes.jdbc2xml.schema.ISchemaEngine; 245 +import org.clazzes.jdbc2xml.schema.ISchemaUpdateSnippet; 246 +import org.clazzes.jdbc2xml.schema.PrimaryKeyInfo; 247 +import org.clazzes.jdbc2xml.schema.TableInfo; 144 144 145 - 249 +public class SchemaUpdate_0_1_01 implements ISchemaUpdateSnippet { 250 + 251 +// This is only accessed through the getter 252 +private static final String TARGET_VERSION = "0.1.01"; 253 + 254 +@Override 255 +public String getTargetVersion() { 256 +return TARGET_VERSION; 257 +} 146 146 147 - 259 +@Override 260 +public String getUpdateComment() { 261 +return "Adding column "+TableDefs.COL_ADDRESSBOOK_GENDER+" to table "+TableDefs.TABLENAME_ADDRESSBOOK+"."; 262 +} 148 148 149 - 264 +@Override 265 +public void performUpdate(ISchemaEngine schemaEngine) throws SQLException { 266 +TableInfo ti = schemaEngine.fetchTableInfo(TableDefs.TABLENAME_ADDRESSBOOK, null); 267 +schemaEngine.addColumn(ti, new ColumnInfo(TableDefs.COL_ADDRESSBOOK_GENDER, Types.VARCHAR, 1, null, true, null)); 268 +} 269 +} 150 150 151 - 152 152 153 - 272 +{{/code}} 273 + 274 +The return values of {{code language="none"}}ISchemaUpdateSnippet.getTargetVersion(){{/code}} and {{code language="none"}}ISchemaUpdateSnippet.getUpdateComment(){{/code}} are written to the {{code language="none"}}SCHEMA_HISTORY{{/code}} table. The update itself is performed in {{code language="none"}}ISchemaUpdateSnippet.performUpdate(){{/code}}. In the above example, it adds a column called {{code language="none"}}GENDER{{/code}} to the ADDRESSBOOK table created via the InitialSchema class above. 275 + 276 +To add an entire table you would use the {{code language="none"}}ISchemaEngine.createTable(){{/code}} method, like this: 277 + 278 +{{code language="java"}} 279 +@Override 280 +public void performUpdate(ISchemaEngine schemaEngine) throws SQLException { 281 + TableInfo tiGroup = new TableInfo(TB_GROUP); 282 + tiGroup.setColumns(Arrays.asList(new ColumnInfo[] { 283 + new ColumnInfo(TableDefs.COL_ID, Types.VARCHAR, 36, null, false, null), 284 + new ColumnInfo(TableDefs.COL_NAME, Types.VARCHAR, 100, null, false, null), 285 + new ColumnInfo(TableDefs.COL_DESCRIPTION, Types.VARCHAR, 512, null, true, null) 286 + })); 287 + tiGroup.setPrimaryKey(new PrimaryKeyInfo(PK_GROUP, TableDefs.COL_ID)); 288 + tiGroup.setIndices(Arrays.asList(new IndexInfo(IDX_GROUP_01, TableDefs.COL_NAME, true, null))); 289 + 290 +schemaEngine.createTable(tiGroup, true); 291 +} 292 +{{/code}} 293 + 294 +Executing a PreparedStatement also works, using ISchemaEngine.getConnection() to retrieve the database connection: 295 + 296 +{{code language="java"}} 297 +@Override 298 +public void performUpdate(ISchemaEngine schemaEngine) throws SQLException { 299 + String sql = "UPDATE "+TableDefs.TB_EXAMPLE_TABLE_NAME+" SET "+TableDefs.COL_EXAMPLE_NAME+"=?"; 300 + 301 + PreparedStatement ps = schemaEngine.getConnection().prepareStatement(sql); 302 + 303 + ps.setNull(1, Types.VARCHAR); 304 + 305 + ps.execute(); 306 +} 307 +{{/code}} 308 + 309 +To create the map of updates in Blueprint/Spring and inject them into SchemaManager, use the following xml-Snippet: 310 + 311 +{{code language="html/xml"}} 312 +<!-- SchemaManager bean definition starts here ... --> 313 +<bp:property name="upateSnippets"> 314 +<bp:map> 315 +<bp:entry key="0.1.00" value="org.clazzes.example.jdbc2xml.updates.SchemaUpdate0_1_01"></bp:entry> 316 +<!-- more entries come here: "key" is the schema version to update, "value" the qualified classname of the schema update --> 317 +</bp:map> 318 +</bp:property> 319 +<!-- ... and continues here --> 320 +{{/code}} 321 + 322 += {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-SchemaMaintainanceStrategies"/}}Schema Maintainance Strategies = 323 + 324 +The JDBC2XML Schema management tools allow for 2 different strategies: 325 + 326 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Frozen(Initial)TableList"/}}Frozen (% style="font-size: 14.0pt;" %)(Initial) Table List(%%) === 327 + 328 +The legacy strategy is: 329 + 330 +(% style="list-style-type: square;" %) 331 +* At the start of a project, create and use {{code language="none"}}InitalSchema.java{{/code}} 332 +* After the first commit, {{code language="none"}}InitalSchema{{/code}} are considered frozen, all changes go into {{code language="none"}}SchemaUpdates{{/code}}, up to one update per source code commit 333 + 334 +Advantage: Rock solid. 335 + 336 +Disadvantage: No place to look for the complete and exact current scheme, except actual databases. {{code language="none"}}TableDefs.java{{/code}} provide some information, but may become confusing in the long term. 337 + 338 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Possiblebutdangerous:Evolving(Initial)TableList"/}}Possible but dangerous: Evolving (Initial) Table List === 339 + 340 +To keep the (Initial) Schema up do date, one might use this strategy: 341 + 342 +(% style="list-style-type: square;" %) 343 +* keep the {{code language="none"}}InitalSchema{{/code}} up to date, so an empty database always gets the current scheme in one shot 344 +* {{code language="none"}}SchemaUpdates{{/code}} are only applied to existing databases 345 + 346 +Advantage: Immediate overview over exact current scheme. 347 + 348 +Disadvantage: Very real danger of messing something up, because 349 + 350 +(% style="list-style-type: square;" %) 351 +* schema updates have to be coded in 2 different places in 2 different ways 352 +* the bean definition has to be maintained in 2 places but just 1 353 + 354 +Conclusion: **DO NOT DO THIS**. This strategy may be ok in very early stages, but at some point it has to be 355 + 356 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Recommendation:FreezeInitialTableDefinitionnotlaterthanthefirstReleaseCandidate(RC)"/}}(% style="font-size: 14.0pt;" %)Recommendation: Freeze Initial Table Definition not later than the first Release Candidate (RC)(%%) === 357 + 358 +It may be ok to start a new project using a fast changing (% style="font-size: 10.0pt;line-height: 13.0pt;" %)(Initial) Table List. 359 + 360 +(% style="font-size: 10.0pt;line-height: 13.0pt;" %)But, please, freeze it at some point. Once the first test server is setup up, internally or at a friendly customer, the Frozen Initial Table List Strategy is the only valid one! 361 + 362 += {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-RealworldExample"/}}Real world Example = 363 + 364 +This HowTo is currently evolving while an additional developer gets acostumed to the SchemaEngine, for developing [[SDS' org.clazzes.sds.impl.schema package>>url:http://svn.clazzes.org/svn/sds/trunk/sds.impl/src/main/java/org/clazzes/sds/impl/schema||style="font-size: 10.0pt;line-height: 13.0pt;" shape="rect"]](% style="font-size: 10.0pt;line-height: 13.0pt;" %) which is **work in progress**! 365 + 366 +(% style="font-size: 10.0pt;line-height: 13.0pt;" %)\\
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... ... @@ -1,1 +1,1 @@ 1 -656 8091 +656798 - URL
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... ... @@ -1,1 +1,1 @@ 1 -https://clazzes.atlassian.net/wiki/spaces/JDBC2XML/pages/656 809/How To create and update Databases using SchemaManager and SchemaUpdateSnippets1 +https://clazzes.atlassian.net/wiki/spaces/JDBC2XML/pages/656798/How To create and update Databases using SchemaManager and SchemaUpdateSnippets