Fix like escaping for DB2, Oracle and MySql (#1162)

* Extended test case to show problem

* FIX: Proper escaping of backslash in like/contains queries

* Had to replace "like ?" assertions in tests with "like " as mysql will do a "like binary ? escape'|'" now to be case sensitive

src/main/java/io/ebean/config/dbplatform/DatabasePlatform.java

@@ -175,7 +175,7 @@ public class DatabasePlatform {
 
   protected SqlExceptionTranslator exceptionTranslator = new SqlCodeTranslator();
 
-  protected char[] specialLikeCharacters = { '%', '_' };
+  protected char[] specialLikeCharacters = { '%', '_', '\\' };
 
   /**
    * Instantiates a new database platform.

src/main/java/io/ebean/config/dbplatform/db2/DB2Platform.java

@@ -26,7 +26,10 @@ public class DB2Platform extends DatabasePlatform {
 
     this.dbIdentity.setSupportsGetGeneratedKeys(true);
     this.dbIdentity.setSupportsSequence(true);
-
+    
+    this.likeClause = "like ? escape '|'";
+    this.specialLikeCharacters = new char[] { '%', '_', '|' };
+    
     this.exceptionTranslator =
       new SqlErrorCodes()
         .addAcquireLock("40001","57033") // key -911/-913
@@ -46,6 +49,10 @@ public class DB2Platform extends DatabasePlatform {
     persistBatchOnCascade = PersistBatch.NONE;
   }
 
+  @Override
+  protected void escapeLikeCharacter(char ch, StringBuilder sb) {
+    sb.append('|').append(ch);
+  }
   /**
    * Return a DB2 specific sequence IdGenerator that supports batch fetching
    * sequence values.

src/main/java/io/ebean/config/dbplatform/mysql/MySqlPlatform.java

@@ -48,6 +48,9 @@ public class MySqlPlatform extends DatabasePlatform {
 
     this.openQuote = "`";
     this.closeQuote = "`";
+    // use pipe for escaping as it depends if mysql runs in no_backslash_escapes or not.
+    this.likeClause = "like binary ? escape '|'";
+    this.specialLikeCharacters = new char[] { '%', '_', '|' };
 
     this.forwardOnlyHintOnFindIterate = true;
     this.booleanDbType = Types.BIT;
@@ -76,4 +79,9 @@ public class MySqlPlatform extends DatabasePlatform {
     // NOWAIT and SKIP LOCKED currently not supported with MySQL
     return sql + " for update";
   }
+  
+  @Override
+  protected void escapeLikeCharacter(char ch, StringBuilder sb) {
+    sb.append('|').append(ch);
+  }
 }

src/main/java/io/ebean/config/dbplatform/oracle/OraclePlatform.java

@@ -37,6 +37,9 @@ public class OraclePlatform extends DatabasePlatform {
 
     this.treatEmptyStringsAsNull = true;
 
+    this.likeClause = "like ? escape '|'";
+    this.specialLikeCharacters = new char[] { '%', '_', '|' };
+    
     this.openQuote = "\"";
     this.closeQuote = "\"";
 
@@ -78,4 +81,9 @@ public class OraclePlatform extends DatabasePlatform {
         return sql + " for update";
     }
   }
+  
+  @Override
+  protected void escapeLikeCharacter(char ch, StringBuilder sb) {
+    sb.append('|').append(ch);
+  }
 }