Support parsing numbers beginning with minus and decimal (e.g. `-.12`)
**BUG**

当前最新分支上，io.shardingjdbc.core.parsing.lexer.Lexer中代码：
```java
private boolean isNumberBegin() {
        return CharType.isDigital(getCurrentChar(0)) || ('.' == getCurrentChar(0) && CharType.isDigital(getCurrentChar(1)) && !isIdentifierBegin(getCurrentChar(-1))
                || ('-' == getCurrentChar(0) && ('.' == getCurrentChar(0) || CharType.isDigital(getCurrentChar(1)))));
    }
```
最后一个判断负数的逻辑，应该是 `('-' == getCurrentChar(0) && ('.' == getCurrentChar(1) || CharType.isDigital(getCurrentChar(1))))`，才能解析出 `-.12` 这种情况


diff --git a/sharding-jdbc-core/src/main/java/io/shardingjdbc/core/parsing/lexer/Lexer.java b/sharding-jdbc-core/src/main/java/io/shardingjdbc/core/parsing/lexer/Lexer.java
index 93c8e3e68fb..aaaac141f63 100755
--- a/sharding-jdbc-core/src/main/java/io/shardingjdbc/core/parsing/lexer/Lexer.java
+++ b/sharding-jdbc-core/src/main/java/io/shardingjdbc/core/parsing/lexer/Lexer.java
@@ -119,7 +119,7 @@ public class Lexer {
     
     private boolean isNumberBegin() {
         return CharType.isDigital(getCurrentChar(0)) || ('.' == getCurrentChar(0) && CharType.isDigital(getCurrentChar(1)) && !isIdentifierBegin(getCurrentChar(-1))
-                || ('-' == getCurrentChar(0) && ('.' == getCurrentChar(0) || CharType.isDigital(getCurrentChar(1)))));
+                || ('-' == getCurrentChar(0) && ('.' == getCurrentChar(1) || CharType.isDigital(getCurrentChar(1)))));
     }
     
     private boolean isSymbolBegin() {
diff --git a/sharding-jdbc-core/src/test/java/io/shardingjdbc/core/parsing/lexer/LexerTest.java b/sharding-jdbc-core/src/test/java/io/shardingjdbc/core/parsing/lexer/LexerTest.java
index 708faf2381a..9bb1968c843 100644
--- a/sharding-jdbc-core/src/test/java/io/shardingjdbc/core/parsing/lexer/LexerTest.java
+++ b/sharding-jdbc-core/src/test/java/io/shardingjdbc/core/parsing/lexer/LexerTest.java
@@ -74,6 +74,7 @@ public final class LexerTest {
         assertNextTokenForNumber("0x-1e", Literals.HEX);
         assertNextTokenForNumber("123", Literals.INT);
         assertNextTokenForNumber("-123", Literals.INT);
+        assertNextTokenForNumber("-.123", Literals.FLOAT);
         assertNextTokenForNumber("123.0", Literals.FLOAT);
         assertNextTokenForNumber("123e4", Literals.FLOAT);
         assertNextTokenForNumber("123E4", Literals.FLOAT);
['sharding-jdbc-core/src/test/java/io/shardingjdbc/core/parsing/lexer/LexerTest.java', 'sharding-jdbc-core/src/main/java/io/shardingjdbc/core/parsing/lexer/Lexer.java']